Question

Alice collected stamps for 7 weeks. She counted the number of stamps in her collection every week. By week 2, there had been 7 stamps collected. How many stamps did Alice collect between week 5 and week 7? A. 5 B. 6 C. 17 D. 22

Answer 1

What we can do to solve this problem is the following rule of three:
 2 weeks ---> 7 stamps
 7 weeks ---> x
 Clearing x we have:
 x = (7/2) * 7 = 24.5
 The other rule of three is:
 2 weeks ---> 7 stamps
 5 weeks ---> x
 Clearing x we have:
 x = (5/2) * (7) = 17.5
 You have the following inequality
 17.5 <x <24.5
 Thus
 x = 22
 answer:
 Alice collect between week 5 and week 7, 22 stamps.
 D.22