Probability worksheet with answers

Free printable Probability worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
xp(x)1?20.3530.3540.1

The table gives the probability distribution of X, but one probability is missing. Find P(X = 1).

x: 1, 2, 3, 4p(x): ?, 0.35, 0.35, 0.1
P(X = 1) =
2.Easy
red: 7blue: 5green: 4

A bag holds 7 red, 5 blue and 4 green balls. You draw one at random. What is the probability P that it is not red?

7 / 5 / 4
P =
3.Medium
P(at least one six) = ??1?2?3?4?5?6?7P(six) = 1/6 on each roll

A fair die is rolled 7 times. What is the probability P of getting at least one six?

n = 7
P =
4.Medium
n = 14k = 5N = ?

In how many ways N can a committee of 5 people be chosen from a group of 14? The order does not matter.

n = 14k = 5
N =
5.Hard
n = 10, p = 0.4: P(X = 3) = ?k012345678910

A test has 10 multiple-choice questions. A student who guesses gets each one right with probability 0.4, independently. What is the probability P of exactly 3 correct answers?

n = 10p = 0.4k = 3
P =
6.Hard
n = 10, p = 0.1: P(X ≤ 1) = ?k012345678910

10 components are tested, and each one fails with probability 0.1, independently. What is the probability P that at most one fails?

n = 10p = 0.1
P =

Answer key

  1. 1. P(X = 1) = 0.2
  2. 2. P = 0.5625
  3. 3. P = 0.7209
  4. 4. N = 2002
  5. 5. P = 0.215
  6. 6. P = 0.7361

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