Problem:
Suppose that 4a=5,5b=6,6c=7, and 7d=8. What is aâ‹…bâ‹…câ‹…d?
Answer Choices:
A. 1
B. 23​
C. 2
D. 25​
E. 3
Solution:
Because
4aâ‹…bâ‹…câ‹…d=(((4a)b)c)d=((5b)c)d=(6c)d=7d=8=43/2
we have a⋅b⋅c⋅d=23​.
Answer: B​.
The problems on this page are the property of the MAA's American Mathematics Competitions