ReasoningAges 13-15

Conditional probability tables

Calculate conditional probability from subgroup counts and express the result as a simplified fraction. Review suitability for your learners before teaching.

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Worksheet StudioPractice pack · Ages 13-15

Conditional probability tables

Take your time. Show your thinking.

1. In a club, 11 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
11 s · 2 · Conditional probability ta…
2. In a club, 12 students play chess, and 5 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
12 s · 5 · Conditional probability ta…
3. In a club, 20 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
20 s · 7 · Conditional probability ta…
4. In a club, 22 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
22 s · 7 · Conditional probability ta…
5. In a club, 12 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
12 s · 2 · Conditional probability ta…
6. In a club, 21 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
21 s · 15 · Conditional probability ta…
7. In a club, 28 students play chess, and 13 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
28 s · 13 · Conditional probability ta…
8. In a club, 22 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
22 s · 15 · Conditional probability ta…
9. In a club, 21 students play chess, and 12 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
21 s · 12 · Conditional probability ta…
10. In a club, 19 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
19 s · 8 · Conditional probability ta…
11. In a club, 13 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
13 s · 8 · Conditional probability ta…
12. In a club, 29 students play chess, and 14 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
29 s · 14 · Conditional probability ta…

12 questions · Seed 55 · Age guidance, not curriculum certification

View the answer key

Worksheet StudioAnswer key · Ages 13-15

Conditional probability tables

Answers and reasoning. Review before teaching.

1. In a club, 11 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
2/11
Out of 11 chess players, 2 play an instrument. Simplifying 2/11 by dividing by 1 gives 2/11.
2. In a club, 12 students play chess, and 5 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
5/12
Out of 12 chess players, 5 play an instrument. Simplifying 5/12 by dividing by 1 gives 5/12.
3. In a club, 20 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
7/20
Out of 20 chess players, 7 play an instrument. Simplifying 7/20 by dividing by 1 gives 7/20.
4. In a club, 22 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
7/22
Out of 22 chess players, 7 play an instrument. Simplifying 7/22 by dividing by 1 gives 7/22.
5. In a club, 12 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
1/6
Out of 12 chess players, 2 play an instrument. Simplifying 2/12 by dividing by 2 gives 1/6.
6. In a club, 21 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
5/7
Out of 21 chess players, 15 play an instrument. Simplifying 15/21 by dividing by 3 gives 5/7.
7. In a club, 28 students play chess, and 13 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
13/28
Out of 28 chess players, 13 play an instrument. Simplifying 13/28 by dividing by 1 gives 13/28.
8. In a club, 22 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
15/22
Out of 22 chess players, 15 play an instrument. Simplifying 15/22 by dividing by 1 gives 15/22.
9. In a club, 21 students play chess, and 12 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
4/7
Out of 21 chess players, 12 play an instrument. Simplifying 12/21 by dividing by 3 gives 4/7.
10. In a club, 19 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
8/19
Out of 19 chess players, 8 play an instrument. Simplifying 8/19 by dividing by 1 gives 8/19.
11. In a club, 13 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
8/13
Out of 13 chess players, 8 play an instrument. Simplifying 8/13 by dividing by 1 gives 8/13.
12. In a club, 29 students play chess, and 14 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
14/29
Out of 29 chess players, 14 play an instrument. Simplifying 14/29 by dividing by 1 gives 14/29.

12 questions · Seed 55 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 13-15

Conditional probability tables

Take your time. Show your thinking.

1. In a club, 11 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
11 s · 2 · Conditional probability ta…
2. In a club, 12 students play chess, and 5 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
12 s · 5 · Conditional probability ta…
3. In a club, 20 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
20 s · 7 · Conditional probability ta…
4. In a club, 22 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
22 s · 7 · Conditional probability ta…
5. In a club, 12 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
12 s · 2 · Conditional probability ta…
6. In a club, 21 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
21 s · 15 · Conditional probability ta…
7. In a club, 28 students play chess, and 13 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
28 s · 13 · Conditional probability ta…
8. In a club, 22 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
22 s · 15 · Conditional probability ta…
9. In a club, 21 students play chess, and 12 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
21 s · 12 · Conditional probability ta…
10. In a club, 19 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
19 s · 8 · Conditional probability ta…
11. In a club, 13 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
13 s · 8 · Conditional probability ta…
12. In a club, 29 students play chess, and 14 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
29 s · 14 · Conditional probability ta…

12 questions · Seed 55 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 13-15

Conditional probability tables

Answers and reasoning. Review before teaching.

1. In a club, 11 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
2/11
Out of 11 chess players, 2 play an instrument. Simplifying 2/11 by dividing by 1 gives 2/11.
2. In a club, 12 students play chess, and 5 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
5/12
Out of 12 chess players, 5 play an instrument. Simplifying 5/12 by dividing by 1 gives 5/12.
3. In a club, 20 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
7/20
Out of 20 chess players, 7 play an instrument. Simplifying 7/20 by dividing by 1 gives 7/20.
4. In a club, 22 students play chess, and 7 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
7/22
Out of 22 chess players, 7 play an instrument. Simplifying 7/22 by dividing by 1 gives 7/22.
5. In a club, 12 students play chess, and 2 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
1/6
Out of 12 chess players, 2 play an instrument. Simplifying 2/12 by dividing by 2 gives 1/6.
6. In a club, 21 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
5/7
Out of 21 chess players, 15 play an instrument. Simplifying 15/21 by dividing by 3 gives 5/7.
7. In a club, 28 students play chess, and 13 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
13/28
Out of 28 chess players, 13 play an instrument. Simplifying 13/28 by dividing by 1 gives 13/28.
8. In a club, 22 students play chess, and 15 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
15/22
Out of 22 chess players, 15 play an instrument. Simplifying 15/22 by dividing by 1 gives 15/22.
9. In a club, 21 students play chess, and 12 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
4/7
Out of 21 chess players, 12 play an instrument. Simplifying 12/21 by dividing by 3 gives 4/7.
10. In a club, 19 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
8/19
Out of 19 chess players, 8 play an instrument. Simplifying 8/19 by dividing by 1 gives 8/19.
11. In a club, 13 students play chess, and 8 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
8/13
Out of 13 chess players, 8 play an instrument. Simplifying 8/13 by dividing by 1 gives 8/13.
12. In a club, 29 students play chess, and 14 of those chess players also play a musical instrument. Given that a student chosen at random plays chess, what is the conditional probability that they also play a musical instrument, as a simplified fraction?
14/29
Out of 29 chess players, 14 play an instrument. Simplifying 14/29 by dividing by 1 gives 14/29.

12 questions · Seed 55 · Age guidance, not curriculum certification