Question

An e-marketing consultant is hired to determine how long customers spend, on average, on a company's website. If the standard deviation is known from previous studies to be approximately 4.2 minutes, determine the number of customers that needs to be sampled in order to determine the mean length of time spent on the company's website, accurate to within a margin of error of 0.7 minutes, at the 5% level of significance.

Answer 1

In this case, we need to sample at least 140 customers.

Step-by-step explanation:

To determine the number of customers that needs to be sampled in order to determine the mean length of time spent on the company's website within a margin of error of 0.7 minutes at the 5% level of significance, we can use the formula for sample size calculation:

n = ((Z * σ)/E)^2

Where n is the sample size, Z is the z-score corresponding to the desired level of significance (in this case, 5% corresponds to a z-score of approximately 1.96), σ is the standard deviation, and E is the margin of error.

Substituting the given values, we have:

n = ((1.96 * 4.2)/0.7)^2

= 139.49

Therefore, we need to sample at least 140 customers in order to determine the mean length of time accurately within a margin of error of 0.7 minutes at the 5% level of significance.