Question -
Answer -
Given:
Total number ofcourses is 9
So out of 9 courses 2courses are compulsory. Student can choose from 7(i.e., 5+2) courses only.
That too out of 5courses student has to choose, 2 courses are compulsory.
So they have to choose3 courses out of 7 courses.
This can be donein 7C3 ways.
By using the formula,
nCr = n!/r!(n – r)!
7C3 = 7! / 3! (7 – 3)!
= 7! / (3! 4!)
= [7×6×5×4!] / (3! 4!)
= [7×6×5] / (3×2×1)
= 7×5
= 35
∴ The total numberof ways of choosing 5 subjects out of 9 subjects in which 2 are compulsory is35 ways.