The question is from CAT Number Theory - Remainders. We need to find out the divisor,N, with the given details. Remainders are consistent for addition, subtraction and multiplication. As long as the divisor is same, you can add two numbers and take the remainder or add the two remainders.
Question 9: Three numbers leave remainders of 43, 47 and 49 on division by N. The sum of the three numbers leaves a remainder 9 on division by N. What are the values N can take?
In this question, the sum of the three numbers should leave a remainder 43 + 47 + 49 = 139. Or, it should be of the form N * k + 139, where K is an integer.
However, it leaves a remainder 9, or it is of the form N * m + 9.
N * k + 139 = N * m + 9
N * (m - k) = 130
Or, N should be a factor of 130. Since the remainders left on division by N are 43, 47 and 49, N should be greater than 49.
The only factors of 130 that are greater than 49 are 65 and 130. So, N can take 2 values – 65 or 130.
The question is "What are the values N can take?"
Choice D is the correct answer.
CAT® (Common Admission Test) is a registered trademark of the Indian Institutes of Management. This website is not endorsed or approved by IIMs.
2IIM Online CAT Coaching
A Fermat Education Initiative,
58/16, Indira Gandhi Street,
Kaveri Rangan Nagar, Saligramam, Chennai 600 093