Step-by-step explanation:
a diameter is always twice the radius.
the only pairs in this list, where one number is twice the other, is :
2.5 and 5
7.6 and 15.2
so,
2.5 is the radius of A
5 is the diameter of A
7.6 is the radius of B
15.2 is the diameter of B
15.7 is then the circumference of A (as the smaller of the remaining 2 numbers).
47.7 is the circumference of B.
this is also proven by the formula for the circumference of a circle : c = 2×pi×r
