I want to know how to get the correct answer and which one i

I want to know how to get the correct answer and which one is it?

0/ 2 pts Question5 What bending Unit Stress is deveolped for a W10x45 with a bending moment Mmax 72.7 k-ft? rrect Answer 17.8 ksi u Answered 3.5 ksi SI none 1.5 ksi

Solution

Formula = MY/I

For W10X45

moment of inertia I = 248 in4

diatnce from nuetral axis (Y) = d/2 = 10.1/2 in.

Stress= (72.7*12*10.1/2)/248

=17.8 Ksi