Question

A joining adhesive is being tested for an engineering part. 200 parts are tested and the proportion of parts with inadequate adhesion is sought. To ensure 98% confidence in the estimated interval of+0.05 around the true population parameter, what must be the size of the sample? The adhesive in 30 tested parts was found to be inadequate. Find the 98% confidence interval using this set Based on the answer from part b. calculate the actual sample size needed so that 98% confidence interval will be within +0.05. a. b. C.

Answer 1

a)

here margin of error E =	0.050
for98% CI crtiical Z          =	2.33
estimated proportion=p=	0.500
required sample size n =	p*(1-p)*(z/E)2=	543.00

(Note: for exact value of z ; this should be 542 if calculated from software)

b)

c)

here margin of error E =	0.050
for98% CI crtiical Z          =	2.33
estimated proportion=p=	0.150
required sample size n =	p*(1-p)*(z/E)2=	277.00