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)0?20.340.160.3

The table gives the probability distribution of X, but one probability is missing. Find P(X = 0).

x: 0, 2, 4, 6p(x): ?, 0.3, 0.1, 0.3
P(X = 0) =
2.Easy
red: 4blue: 2green: 5

A bag holds 4 red, 2 blue and 5 green balls. You draw one at random. What is the probability P that it is red?

4 / 2 / 5
P =
3.Medium
n = 12k = 3N = ?

In how many ways N can a committee of 3 people be chosen from a group of 12? The order does not matter.

n = 12k = 3
N =
4.Medium
n = 14k = 3N = ?

In how many ways N can a committee of 3 people be chosen from a group of 14? The order does not matter.

n = 14k = 3
N =
5.Hard
€p(x)−50.75150.2950.05

A game costs €5 to play. You win €20 with probability 0.2 and €100 with probability 0.05; otherwise you win nothing. The stake is not returned. Find the expected net gain E(G) per game.

stake = €5€20: p = 0.2€100: p = 0.05
E(G) = €
6.Hard
€p(x)−50.89150.1950.01

A game costs €5 to play. You win €20 with probability 0.1 and €100 with probability 0.01; otherwise you win nothing. The stake is not returned. Find the expected net gain E(G) per game.

stake = €5€20: p = 0.1€100: p = 0.01
E(G) = €

Answer key

  1. 1. P(X = 0) = 0.3
  2. 2. P = 0.3636
  3. 3. N = 220
  4. 4. N = 364
  5. 5. E(G) = 4 €
  6. 6. E(G) = −2 €

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