Source: Official Guide for the GMAT 13th Ed. Problem Solving; #113 Official Guide for the GMAT 2015 14th Ed. Problem Solving; #113

1

In a certain district, the ratio of

In a certain district, the ratio of the number of registered Republicans to the number of registered Democrats was 3/5. After 600 additional Republicans and 500 additional Democrats registered, the ratio was 4/5. After these registrations, there were how many more voters in the district registered as Democrats than as Republicans?

3 Explanations

1

SONIKA VASANTH

While solving you have taken 3/5ths of 1000 but that is the ratio of R/D not the value of R. So how can we multiply 3/5ths of 1000. Did i miss anything.

Thanks in advance

Dec 7, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Hi Sonika,

Happy to help! Notice how Mike solves for the number of registered democrats:

1000 = # Democrats registered

So, we can set up the following proportion:

3/5 = R/1000

where R is the original number of Republicans registered.

To solve for R, we can multiply both sides by 1000:

1000*3/5 = R
3000/5 = R
600 = R

There were therefore 600 Republicans originally registered.

I hope this clears up your doubts about this step in the solution :)

Dec 9, 2016 • Reply

1

Joseph Lucaj

Im confused about the question stem. It say "there were how many more".... I understood it as prior to the additional registered R&D can you help clear it up?

Jun 21, 2015 • Comment

Jonathan , Magoosh Tutor

Hi Joseph. Note that the question says "After these registrations" :

After these registrations, there were how many more voters in the district registered as Democrats than as Republicans?

So we are talking about AFTER the additional R&D registered.

Jun 29, 2015 • Reply

2

Gravatar Mike McGarry, Magoosh Tutor

Dec 28, 2013 • Comment

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