To determine the effect of 100% nitrate on the

growth of pea plants, several specimens were planted and

then watered with 100% nitrate every day. At the end of

two weeks, the plants were measured. Here are data on

seven of them:

17.5 14.5 15.2 14.0 17.3 18.0 13.8

Assume that these data are a random sample from a

normal distribution N(, 2).

(a) Find the value of a point estimate of .

(b) Find the value of a point estimate of .

(c) Give the endpoints for a 90% confidence interval

for .