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, 20 students play chess, and 6 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 · 6 · Conditional probability ta…
2. In a club, 17 students play chess, and 10 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?
17 s · 10 · Conditional probability ta…
3. In a club, 24 students play chess, and 10 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?
24 s · 10 · Conditional probability ta…
4. In a club, 19 students play chess, and 4 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 · 4 · Conditional probability ta…
5. In a club, 12 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?
12 s · 7 · Conditional probability ta…
6. In a club, 20 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?
20 s · 12 · Conditional probability ta…
7. In a club, 26 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?
26 s · 12 · Conditional probability ta…
8. In a club, 10 students play chess, and 6 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?
10 s · 6 · Conditional probability ta…
9. 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…
10. In a club, 11 students play chess, and 4 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 · 4 · Conditional probability ta…
11. In a club, 21 students play chess, and 9 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 · 9 · Conditional probability ta…
12. In a club, 15 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?
15 s · 8 · Conditional probability ta…

12 questions · Seed 104731 · 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, 20 students play chess, and 6 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?
3/10
Out of 20 chess players, 6 play an instrument. Simplifying 6/20 by dividing by 2 gives 3/10.
2. In a club, 17 students play chess, and 10 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?
10/17
Out of 17 chess players, 10 play an instrument. Simplifying 10/17 by dividing by 1 gives 10/17.
3. In a club, 24 students play chess, and 10 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 24 chess players, 10 play an instrument. Simplifying 10/24 by dividing by 2 gives 5/12.
4. In a club, 19 students play chess, and 4 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?
4/19
Out of 19 chess players, 4 play an instrument. Simplifying 4/19 by dividing by 1 gives 4/19.
5. In a club, 12 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?
7/12
Out of 12 chess players, 7 play an instrument. Simplifying 7/12 by dividing by 1 gives 7/12.
6. In a club, 20 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?
3/5
Out of 20 chess players, 12 play an instrument. Simplifying 12/20 by dividing by 4 gives 3/5.
7. In a club, 26 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?
6/13
Out of 26 chess players, 12 play an instrument. Simplifying 12/26 by dividing by 2 gives 6/13.
8. In a club, 10 students play chess, and 6 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?
3/5
Out of 10 chess players, 6 play an instrument. Simplifying 6/10 by dividing by 2 gives 3/5.
9. 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.
10. In a club, 11 students play chess, and 4 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?
4/11
Out of 11 chess players, 4 play an instrument. Simplifying 4/11 by dividing by 1 gives 4/11.
11. In a club, 21 students play chess, and 9 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?
3/7
Out of 21 chess players, 9 play an instrument. Simplifying 9/21 by dividing by 3 gives 3/7.
12. In a club, 15 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?
8/15
Out of 15 chess players, 8 play an instrument. Simplifying 8/15 by dividing by 1 gives 8/15.

12 questions · Seed 104731 · Age guidance, not curriculum certification

Worksheet StudioPractice pack · Ages 13-15

Conditional probability tables

Take your time. Show your thinking.

1. In a club, 20 students play chess, and 6 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 · 6 · Conditional probability ta…
2. In a club, 17 students play chess, and 10 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?
17 s · 10 · Conditional probability ta…
3. In a club, 24 students play chess, and 10 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?
24 s · 10 · Conditional probability ta…
4. In a club, 19 students play chess, and 4 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 · 4 · Conditional probability ta…
5. In a club, 12 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?
12 s · 7 · Conditional probability ta…
6. In a club, 20 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?
20 s · 12 · Conditional probability ta…
7. In a club, 26 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?
26 s · 12 · Conditional probability ta…
8. In a club, 10 students play chess, and 6 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?
10 s · 6 · Conditional probability ta…
9. 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…
10. In a club, 11 students play chess, and 4 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 · 4 · Conditional probability ta…
11. In a club, 21 students play chess, and 9 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 · 9 · Conditional probability ta…
12. In a club, 15 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?
15 s · 8 · Conditional probability ta…

12 questions · Seed 104731 · Age guidance, not curriculum certification

Worksheet StudioAnswer key · Ages 13-15

Conditional probability tables

Answers and reasoning. Review before teaching.

1. In a club, 20 students play chess, and 6 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?
3/10
Out of 20 chess players, 6 play an instrument. Simplifying 6/20 by dividing by 2 gives 3/10.
2. In a club, 17 students play chess, and 10 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?
10/17
Out of 17 chess players, 10 play an instrument. Simplifying 10/17 by dividing by 1 gives 10/17.
3. In a club, 24 students play chess, and 10 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 24 chess players, 10 play an instrument. Simplifying 10/24 by dividing by 2 gives 5/12.
4. In a club, 19 students play chess, and 4 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?
4/19
Out of 19 chess players, 4 play an instrument. Simplifying 4/19 by dividing by 1 gives 4/19.
5. In a club, 12 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?
7/12
Out of 12 chess players, 7 play an instrument. Simplifying 7/12 by dividing by 1 gives 7/12.
6. In a club, 20 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?
3/5
Out of 20 chess players, 12 play an instrument. Simplifying 12/20 by dividing by 4 gives 3/5.
7. In a club, 26 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?
6/13
Out of 26 chess players, 12 play an instrument. Simplifying 12/26 by dividing by 2 gives 6/13.
8. In a club, 10 students play chess, and 6 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?
3/5
Out of 10 chess players, 6 play an instrument. Simplifying 6/10 by dividing by 2 gives 3/5.
9. 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.
10. In a club, 11 students play chess, and 4 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?
4/11
Out of 11 chess players, 4 play an instrument. Simplifying 4/11 by dividing by 1 gives 4/11.
11. In a club, 21 students play chess, and 9 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?
3/7
Out of 21 chess players, 9 play an instrument. Simplifying 9/21 by dividing by 3 gives 3/7.
12. In a club, 15 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?
8/15
Out of 15 chess players, 8 play an instrument. Simplifying 8/15 by dividing by 1 gives 8/15.

12 questions · Seed 104731 · Age guidance, not curriculum certification