Question

If the probability of selecting a defective bolt is 0.1, find (1) the mean (2) the variance for the distribution of defective bolts in a total of 400.

Answer 1

Answer:

Mean = 40

variance = 36

Step-by-step explanation:

probability of selecting a defective bolt is 0.1

=> p = 0.1

& q = 1 - 0.1 = 0.9

n = 400

Mean = np  = 400 * 0.1 = 40

Variance = npq  = 400 * 0.1 * 0.9 = 36

Standard deviation = √Variance = √36  = 6

Mean = 40

variance = 36