Question

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Answer 1

This is a binomial event. There are only two outcomes either require warranty service within a year or they don't. Each event is an independent trial.

p = 8% = 0.08 n= 11

a)

(n =11 ,p = 0.08 )

~ Bin

P( X =x) =

NI nCr*p* (1-p)"

                = 11Cx * 0.08^x * 0.92^(11-x)

We need to find for x = 2

P(X = 2) = 11C2 * 0.08² * 0.92^(11-2)

Ans: 0.1662

b)

The following formulas are for parameters of the binomial distribution

E(X) =np

E(X) = 0.88

V(X) = np(1-p)

=0.8096

SD(X) =

Var

SD(X) = 0.8998