To find the 95% confidence interval and sample size.
A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighted 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% 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% confidence?
c) Discuss factors which might cause variation in the weight of Tootsie Rolls during manufacture.