A department store has determined that 25% of all their sales are credit sales. A random sample of 75 sales is selected and the proportion of credit sales in the sample is computed.(adsbygoogle = window.adsbygoogle || []).push({});

a) What is the probability that the sample proportion will be greater than 0.34?

my answer is:

n=75 p=0.25

mu=np=18.75

sigma=sqrt(n*p*(1-p)) = 3/75

0.34 * 75=25.5

z=x-mu/sigma = 25.5-18.75/3.75 =1.8

P(z>1.8)=0.0359

the answer i got is 0.0359 but i am not confident, please tell me if i am correct or not. Thanks.

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# Homework Help: Mean and standard deviation probability help

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