The circumference of the two circles is 77 cm and 154 cm, respectively. What is the difference between their radii?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 12.25 cm.
Let the radii of the two circles be r1 and r2, respectively.
2πr1 = 77
⇒ r1 = 77/(2π)
2πr2 = 154
⇒ r2 = 154/(2π)
Difference between their radii = r2 - r1 = 154/(2π) - 77/(2π)
= 77/(2π)
= 77/(2 × 22/7)
= 49/4
= 12.5 cm