Hi all totally new here. I have not done maths for thirty years and find myself stuck with this one.

The ages of all new mothers have a mean of 30.0 years and a standard deviation of 3.0 years.

Provide answers correct to one decimal place below (e.g. 4.0 for 4.0%).

Assuming that the data is normally distributed, the percentage of new mothers aged less than 24.5 years is % in the population.

Using 95% rule of 2 standard deviations either side of the mean mothers less than 24 would = 2.5%. But what do you do when you are asked to work it out to something that does not fit the stasndar deviation. i.e. 24.5

Thanks in advance for any help