The state test scores for 12 randomly selected high school seniors are shown :

Complete parts (a) through (c) below.

Assume the population is normally distributed.

1423	1229	987
692	726	833
724	742	541
628	1444	946

(a) Find the sample mean.

x=

(Round to one decimal place as needed.)

(b) Find the sample standard deviation.

s=

(Round to one decimal place as? needed.)

(c) Construct a 90% confidence interval for the population mean

A 90% confidence interval for the population mean is ( , ).

(Round to one decimal place as needed.)