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)00.351?20.35

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

x: 0, 1, 2p(x): 0.35, ?, 0.35
P(X = 1) =
2.Easy
red: 4blue: 4green: 2

A bag holds 4 red, 4 blue and 2 green balls. You draw one at random. What is the probability P that it is not red?

4 / 4 / 2
P =
3.Medium
red: 5blue: 4

A bag holds 5 red and 4 blue balls. You draw two balls without putting the first one back. What is the probability P that both are red?

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

In how many ways N can a committee of 4 people be chosen from a group of 7? The order does not matter.

n = 7k = 4
N =
5.Hard
€p(x)−20.880.15180.05

A game costs €2 to play. You win €10 with probability 0.15 and €20 with probability 0.05; otherwise you win nothing. The stake is not returned. Find the expected net gain E(G) per game.

stake = €2€10: p = 0.15€20: p = 0.05
E(G) = €
6.Hard
n = 11, p = 0.1: P(X = 2) = ?k01234567891011

A test has 11 multiple-choice questions. A student who guesses gets each one right with probability 0.1, independently. What is the probability P of exactly 2 correct answers?

n = 11p = 0.1k = 2
P =

Answer key

  1. 1. P(X = 1) = 0.3
  2. 2. P = 0.6
  3. 3. P = 0.2778
  4. 4. N = 35
  5. 5. E(G) = 0.5 €
  6. 6. P = 0.2131

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