Question

A farmer finds that the weights of sheep on his farm have a normal distribution with mean 66.4 kg
and standard deviation 5.6 kg.
250 sheep are chosen at random. Estimate the number of sheep which have a weight of between
70 kg and 72.5 kg.

Answer 1

You can play around with Z table stuff at
davidmlane.com/hyperstat/z_table.html

Answer 2

70 kg is [(70 - 66.4) / 5.6] s.d. above the mean

72.5 kg is [(72.5 - 66.4) / 5.6] s.d. above the mean

calculate the two z-scores (s.d. above the mean)
... then use a table to find the portion of the population between the scores

Answer 3

I need to know how to do.I tried it and got 0.13128, but the answer is 0.1221.

Answer 4

Do we need continuity correction also?If yes then why?

Answer 5

there is a z-score calculator at calculator.net

it gives greater precision than the tables
... no need for interpolation from table values