Question

3. From a set of 1000 observations known to be normally distributed, the mean is 534 cm and SD is 13.5 cm. How many observations are likely to exceed 561 cm? How many will be between 520.5 cm and 547.5 cm? Between what limits will the middle 50% of the observations lie?
Reiny
My favourite webpage for this type of question is

http://davidmlane.com/hyperstat/z_table.html

Just enter the data as is, you don't even need to convert them to z scores.