what is katie's mark if she scored above the mean?

Question

a teacher is analyzing the results for a test, the marks are normally distributed with a mean of 77.4 and a standard deviation of 4.2. determine katie's mark if she scores 2.5 standard deviations above the mean.

Answer 1

Then her z-score is 0 + 2.5*1 = = 2.5

(x-mean)/stdDev = z ----> x = z*stndDev+ mean

= 2.5 * 4.2 + 77.4

= 87.9