When the Numbers 5, 7, 11 Divide a Positive Multiple of 17, the Remainders Left GMAT Problem Solving

Question: When the numbers 5, 7, 11 divide a positive multiple of 17, the remainders left are respectively 4, 6, and 10. Which positive multiple of 17 gives the least number that satisfies the given condition?

  1. 315th
  2. 316th
  3. 317th
  4. 384th
  5. 385th

Solution and Explanation

Approach Solution (1):

We can see that the difference between the divisor and remainder is constant = 1
5 – 4 = 1
7 – 6 = 1
11 – 10 = 1
So the least number will be 1 less than the LCM (5, 7, 11)
LCM (5, 7, 11) = 385, Least such number = 385 – 1 = 384
Since the number has to be a multiple of 17, it will be of the form 385n – 1 = 17k
The least such number is 5389 = 17 * 317

Correct option: C

Approach Solution (2):

In this question, we will use the Units Digit Analysis Method.
We will start with the first three answer choices.
1st positive multiple of 17 = 1 * 17 = 17
2nd positive multiple of 17 = 2 * 17 = 34
And so on
We are looking for the least positive multiple of 17
Given: 17m = 385k – 1
This can be written as: 385k = 17m + 1
On the LHS of the equation, the factor 385 multiplied by any non-negative integer k will yield a Units Digit of either 0 or 5.
Therefore, the RHS must yield a Units Digit of 0 and 5
This can also be read as: 17m + 1 must yield a Units Digit of 0 and 5
(1) 315th positive multiple of 17
(17) (315) + 1 (units digit of 6)

(2) 316th positive multiple of 17
(17) (316) + 1 (units digit of 3)

(3) 317th positive multiple of 17
(17) (317) + 1 (units digit of 0)

(4) 384th positive multiple of 17
(17) (384) + 1 (units digit of 9)

(5) 385th positive multiple of 17
(17) (385) + 1 (units digit of 6)

The only possible answer that could work is (c) 317th positive multiple of 17 = 5, 389

Correct option: C

Approach Solution (3):

Given:\(\frac{(17*Unkown)}{5}\)
Remainder: 4
Multiply each no's last digit by 7 if 17, we will get:

A. 315th: 7*5 = 35 =\(\frac{35}{5} \)(Perfectly divide, no remainder)
B. 316th: 7*6 = 42 =\(\frac{30}{5}\)(Perfectly divide, remainder= 2)
C. 317th: 7*7 = 49 =\(\frac{49}{5}\)(Perfectly divide, remainder= 4)
D. 384th: 7*4 = 28 =\(\frac{28}{5}\)(Perfectly divide, remainder= 3)
E. 385th: 7*5 = 35 =\(\frac{35}{5}\)(Perfectly divide, no remainder)

Correct option: C

“When the numbers 5, 7, 11 divide a positive multiple of 17, the remainders left are respectively 4, 6, and 10. Which positive multiple of 17 gives the least number that satisfies the given condition?”- is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been taken from the book “GMAT Official Guide Quantitative Review”. To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. The GMAT Quant topic in the problem-solving part requires calculative mathematical problems that should be solved with proper mathematical knowledge.

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