Give a 90% confidence interval for the true proportion of those from their entire mailing list who may donate. (b) A staff member thinks that the true rate is 4.8%. Given the confidence interval you found, do you find that rate plausible?

a) The 90% CI for the true rate is [4.44%, 4.65%].

b) The rate of 4.8% is not plausible.

Step-by-step explanation:

The question is incomplete:

A philanthropic organization sent free mailings labels to a random sample of 100,000 potential donors and received 4,545 donations.

Give a 90% confidence interval for the true proportion of those from their entire mailing list who may donate. (b) A staff member thinks that the true rate is 4.8%. Given the confidence interval you found, do you find that rate plausible?

The proportion of the sample is:

The estimated standard deviation is

The z-value for a 90% confidence interval is z=1.645.

Then, the CI can be constructed as:

The 90% CI for the true rate is [4.44%, 4.65%].

b) The value 4.8% lies outside the 90% confidence interval (more specifically, over the upper limit), so it has less than 5% of probability of being the true rate.

The rate of 4.8% is not plausible.

∈3,600

step-by-step explanation: