C/D = 9.75 when dividing positive integer C by positive

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AAPL: Moderator; Posts: 2599; Joined: Sun Oct 29, 2017 2:08 pm; Followed by:2 members

C/D = 9.75 when dividing positive integer C by positive

by AAPL » Wed May 09, 2018 7:02 am

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C/D = 9.75 when dividing positive integer C by positive integer D, the remaining is 3. Which of the following could be the value of C?

A. 39
B. 37
C. 36
D. 31
E. 30

The OA is A.

C/D = 9.75 = 975/100

Divide numerator/denominator by 25
= 39/4 which gives remainder of 3

The correct answer is A.

Has anyone another approach to solve this PS question? Regards!

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Source: Beat The GMAT — Problem Solving | Wed May 09, 2018 7:02 am

GMAT/MBA Expert

Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pm; Location: Vancouver, BC; Thanked: 5254 times; Followed by:1268 members; GMAT Score:770

by Brent@GMATPrepNow » Wed May 09, 2018 12:45 pm

AAPL wrote:C/D = 9.75 when dividing positive integer C by positive integer D, the remaining is 3. Which of the following could be the value of C?

A. 39
B. 37
C. 36
D. 31
E. 30

IMPORTANT: There are infinitely many pairs of values of C and D that satisfy the condition that C/D = 9.75
For example, 975/100 = 9.75. In this case, C = 975 and D = 100
Likewise, 195/20 = 9.75. In this case, C = 195 and D = 20
Also, 390/40 = 9.75. In this case, C = 390 and D = 40
And 39/4 = 9.75. In this case, C = 39 and D = 4
etc.

In fact, ALL fractions that are equivalent to 975/100 will satisfy the condition that C/D = 9.75
Of course, we're also told that, when we divide C by D, the remainder is 3.
So, let's check some of our possible cases.

If C = 975 and D = 100, then the remainder is 75 when we divide C by D. NO GOOD
If C = 195 and D = 20, then the remainder is 15 when we divide C by D. NO GOOD
If C = 39 and D = 4, then the remainder is 3 when we divide C by D. BINGO!!!

Answer: A

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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GMAT/MBA Expert

Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Thu May 10, 2018 4:57 pm

AAPL wrote:C/D = 9.75 when dividing positive integer C by positive integer D, the remaining is 3. Which of the following could be the value of C?

A. 39
B. 37
C. 36
D. 31
E. 30

Simplifying the equation we have:

C/D = 9 + 0.75

C/D = 9 + 75/100

C/D = 9 + 3/4

We can also say that:

C/D = Q + 3/D

Since 3/4 = 3/D, we see that D = 4.

Thus, we see that C/4 = 9.75, so C = 4 x 9.75 = 39.

Answer: A

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