Query about Question 11 from "(I'm Overwhelmed) Arithmetic Progress Quiz #5" [6962]

GRE GRE Quant Problem Solving
1

https://www.gregmat.com/quizzes/quiz/im-overwhelmed-arithmetic-progress-quiz-5 (Question 11)

I didn’t understand the solution to this question. Could you pls explain

2

Do you know how to count the number of even and odd divisors for an integer like n = 2^a \cdot p_1^b, where p_1 is an odd prime?

3

Yes

4

What would it be?

5

b+1??

6

Sure, that’s the number of odd divisors. What about the number of even divisors?

7

That will be total - odd or odd divisors x exponent of 2?