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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Name: ____________________   Date: ____________

1.Easy
red: 5blue: 5green: 5

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

5 / 5 / 5
P =
2.Easy
red: 4blue: 4green: 1

A bag holds 4 red, 4 blue and 1 green balls. You draw one at random. What is the probability P that it is blue?

4 / 4 / 1
P =
3.Medium
xp(x)00.210.2520.3530.2μ = 1.55

For the distribution shown, find the standard deviation σ of X.

x: 0, 1, 2, 3p(x): 0.2, 0.25, 0.35, 0.2
σ =
4.Medium
P(at least one six) = ??1?2?3?4?5?6P(six) = 1/6 on each roll

A fair die is rolled 6 times. What is the probability P of getting at least one six?

n = 6
P =
5.Hard
xp(x)100.15200.35300.3400.2μ

X has the distribution shown, and Y = 0.5X + 20. Find the standard deviation σY of Y.

x: 10, 20, 30, 40p(x): 0.15, 0.35, 0.3, 0.2Y = 0.5X + 20
σY =
6.Hard
n = 7, p = 0.25: P(X = 4) = ?k01234567

A test has 7 multiple-choice questions. A student who guesses gets each one right with probability 0.25, independently. What is the probability P of exactly 4 correct answers?

n = 7p = 0.25k = 4
P =

Answer key

  1. 1. P = 0.6667
  2. 2. P = 0.4444
  3. 3. σ = 1.023
  4. 4. P = 0.6651
  5. 5. σY = 4.867
  6. 6. P = 0.05768

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