Question: The weight of adult wombats at a park are estimated to be normally distributed with mean 30KG and Standard deviation 5kg. A random sample of 200 adult wombats were taken from this population to be weighed and tagged. The scales have broken and here are tooo many to take to the research station. Suggest that they can expect the number weighing less than 25kg to be approximately:
a. 64
b. 100
c. 68
d. 32
Can someone tell me how do to this?? please show your working in detail :( thanksss
a. 64
b. 100
c. 68
d. 32
Can someone tell me how do to this?? please show your working in detail :( thanksss

The mean is 30 and sd is 5. And so, 25 is one sigma below mean. And so, for normal distribution, below 25 we will find 0. 1587 probability (table value).
Thus, 200x0.1587 = 32 wombats are expected to have less than 25kg weight.
:)
Thus, 200x0.1587 = 32 wombats are expected to have less than 25kg weight.
:)