read the description . I need work and an explanation

Question

Tom and Jan are planning on applying to attend KSU. Tom takes the ACT while Jan decides to take the SAT. The mean score on the ACT is a 17 with a standard deviation of 5, and the SAT mean score is an 1100 with a standard deviation of 155. Tom received his score of 19, and Jan got a 1175. Who had the overall better score?

Answer 1

The Z score for TOM is  (19-17)/5 = 2/5 = 0.4 

So Tom scores 0.4 standard deviations above the mean

 

The Z score for JAN is (1175 - 1100)/155 = 75/155 = 0.48

SO Jan scores 0.48 standard deviations above the mean

 

Jan's score is slightly better