Let X equal the excess weight of soap in a "1000-gram" bottle. Assume that the distribution...

Let X equal the excess weight of soap in a "1000-gram" bottle. Assume that the distribution of XN(μ,180).

What sample size is required so that we have 95% confidence that the maximum error of the estimate of μ is 1.7?

Sample size required= ?

Solutions

Expert Solution

given , σ² =180

σ=√σ² = √180 = 13.4164

sampling error ,    E =   1.7
Confidence Level ,   CL=   95%

alpha =   1-CL =   5%
Z value =    Zα/2 =    1.960   [excel formula =normsinv(α/2)]

Sample Size,n = (Z * σ / E )² = (   1.960   *   13.4164 /   1.7   ) ² =   239.3


So,Sample Size needed=       240

orchestra answered 1 year ago

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