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Question
The probability of defective bolts in a workshop is 40%. Find the mean and variance of defective bolts out of 10 bolts.
Solution
Let X denote the number of defective bolts.
p = probability of defective bolts.
p = 40%
p = `40/100` = 0.4
q = 1 -p = 0.6
Here n = 10
E (X) = np
= 10 x 0.4
= 4
V(X) = npq
= 4 x 0.6
= 2.4
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