Question

Sarah works for a coffee company. The farmers who supply the company spray Chemical X as a pesticide. the company brings in 2million pounds of coffee a year, and they take a sample of beans every 10,000lbs to ensure that levels of Chemical X are around 3ppm.

Last year the average ppm of Chemical X was 2.43, with a standard deviation of 3.848.

a) What is the statistical power of the current sampling scheme?

b) how many samples does Sarah need to take to be 85% sure that Chemical X doesnt differ from 3ppm by more than 1.5ppm in either direction?

Answer 1