If the distribution of life spans in Exercise: 10.21 is approximately normal, how large a sample: is

Question:

If the distribution of life spans in Exercise: 10.21 is approximately normal, how large a sample: is required in order that the probability of committing a type 11 error be 0.1 when the true mean is 35.9 months? Assume that a = 5.8 months.

Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...