The amount of fill (weight of contents) put into a glass jar of spaghetti sauce is normally distributed with mean ì = 843 grams and standard deviation of ó = 9 grams

(d) Find the mean of the x distribution. (Give your answer correct to the nearest whole number.)
843 Was my answer.

(ii) Find the standard error of the x distribution. (Give your answer correct to two decimal places.)
Not sure of formula to work this one

(e) Find the probability that a random sample of 20 jars has a mean weight between 836 and 855 grams. (Give your answer correct to four decimal places.)
Not sure of formula to work this one

1 answer

2) SEm = SD/√n

e) Z = (score-mean)/SEm

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.