Question

37 The diameter of circle X is 15 centimeters. The diameter of circle Y is 20 centimeters.

Which measurement is closest to the difference between the circumference of circle X and the
circumference of circle Y in centimeters?
A 15.7 cm
B 7,85 cm
C 137 cm
D 31.4 cm

Answer 1

cual es la respuesta de esta pregunta

Answer 2

A

Explanation:

this can be done without any calculator, which I did and explain below :

the circumference of a circle is always

2×pi×r

with r being the radius, which is always half of the diameter.

so, the circle X circumference is

pi×15

circle Y

pi×20

the difference is

20×pi - 15×pi = 5×pi

5×pi is half of 10×pi, which would be 10×3.1415... = 31.415...

half of that is about 15.7.

so, A is the correct answer