Top 24% means that you have to be better than 100 - 24 = 76%.
In decimal, it is
76/100 = 0.76
This is the z-score of a normal distribution.
The formula for z-score is:
Where
x is the raw data value
mu is the mean
sigma is the standard deviation
Since, this is a normal distribution, the mean is 0 and standard deviation 1. Also, z-score is 0.76. From z-score table, we have:
[tex]\begin{gathered} P(x
Roundiing to 2 decimal places, that is 0.71 standard deviations