JIPMAT 2023
Number System
Miscellaneous
Medium
Amicable numbers are a pair of distinct natural numbers (a, b) such that the sum of the proper divisors of a equals b and the sum of the proper divisors of b equals a. Given that (220, y) is a pair of amicable numbers, y equals:
Amicable numbers are a pair of distinct natural numbers (a, b) such that the sum of the proper divisors of a equals b and the sum of the proper divisors of b equals a. Given that (220, y) is a pair of amicable numbers, y equals:
Correct Option: 2
1) First, let's find all proper divisors of 220: * Proper divisors are all positive divisors excluding the number itself * Factors of 220 = 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110, 220 * Proper divisors of 220 = 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110 * Sum of proper divisors of 220 = 2842) Let's check each option:If y = 225: * Proper divisors of 225 = 1, 3, 5, 9, 15, 25, 45, 75 * Sum = 178 * Since 178 ≠ 220, 225 is not correctIf y = 284: * Proper divisors of 284 = 1, 2, 4, 71, 142 * Sum = 220 * Since sum of proper divisors of 220 = 284 AND * Sum of proper divisors of 284 = 220 * This makes (220, 284) an amicable pair!No need to check 404 since we found our answer.Therefore, y = 284.
Related questions: