Binomial mean and SD: practice

Statistics. Try each one, then open the answer. The Credit Sprint app generates unlimited new versions.

Item 1.

X is binomial with n = 50 and p = 0.2. What is the mean of X?

Show answer

Mean = np = 50 × 0.2 = 10.

Item 2.

X is binomial with n = 25 and p = 0.1. What is the standard deviation of X (round to 2 decimals)?

Show answer

SD = √(np(1−p)) = √(25×0.1×0.9) ≈ 1.5.

Item 3.

X is binomial with n = 25 and p = 0.5. What is the standard deviation of X (round to 2 decimals)?

Show answer

SD = √(np(1−p)) = √(25×0.5×0.5) ≈ 2.5.

Item 4.

X is binomial with n = 40 and p = 0.25. What is the mean of X?

Show answer

Mean = np = 40 × 0.25 = 10.

Item 5.

X is binomial with n = 50 and p = 0.1. What is the standard deviation of X (round to 2 decimals)?

Show answer

SD = √(np(1−p)) = √(50×0.1×0.9) ≈ 2.12.

Item 6.

X is binomial with n = 40 and p = 0.5. What is the standard deviation of X (round to 2 decimals)?

Show answer

SD = √(np(1−p)) = √(40×0.5×0.5) ≈ 3.16.