A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were

3.087

3.131

3.241

3.241

3.270

3.353

3.400

3.411

3.437

3.477

(a) Construct a 90 percent confidence interval for the true mean weight.

(b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence?

This is what I got so far? Im lost!

3.3115 ± 1.645 (0.131988888)/√10 =