Problem Solving

LUANDATO wrote:A computer store sells two sizes of laptops, 13-inch and 15-inch. During a typical week, the store sells two 13-inch laptops for every 15-inch laptop. However, during the holiday season, the number of 13-inch laptops sold decreases by 50 percent, and the number of 15-inch laptops sold triples. If the store sells 600 laptops per week during the holiday season, how many more 15-inch laptops than 13-inch laptops are sold?

A. 100
B. 150
C. 200
D. 300
E. 400

The OA is D.

Can any expert explain this PS question please? Thanks.

Say the number of 15" laptops sold per week = x, thus, the number of 13" laptops sold per week = 2x.

Thus, in holiday seasons, the number of 15" laptops sold per week = 3x, and the number of 13" laptops sold per week = 2x/2 = x.

Total sales in a holiday week = 3x + x = 4x

Thus, 4x = 600 => x = 150 and 3x = 450.

The number of 15-inch laptops sold more than 13-inch laptops = 3x - x = 2x = 2*150 = 300.

The correct answer: D

Hope this helps!

-Jay

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide
_________________
Manhattan Review GMAT Prep

Locations: New York | New Delhi | Seoul | Cairo | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.

BTGmoderatorLU wrote:A computer store sells two sizes of laptops, 13-inch and 15-inch. During a typical week, the store sells two 13-inch laptops for every 15-inch laptop. However, during the holiday season, the number of 13-inch laptops sold decreases by 50 percent, and the number of 15-inch laptops sold triples. If the store sells 600 laptops per week during the holiday season, how many more 15-inch laptops than 13-inch laptops are sold?

A. 100
B. 150
C. 200
D. 300
E. 400

The OA is D.

Can any expert explain this PS question please? Thanks.

Our initial ratio of the 13-inch to 15-inch laptops is:

2x : x

During the holiday season, the new ratio becomes:

x : 3x

Since 600 are sold:

x + 3x = 600

4x = 600

x = 150

So, 3(150) = 450 15-inch laptops and 150 13-inch laptops are sold during the holiday season and therefore, 450 - 150 = 300 more 15-inch laptops are sold than 13-inch laptops.

Answer: D

BTGmoderatorLU wrote: ↑

Sat Oct 21, 2017 3:10 pm

A computer store sells two sizes of laptops, 13-inch and 15-inch. During a typical week, the store sells two 13-inch laptops for every 15-inch laptop. However, during the holiday season, the number of 13-inch laptops sold decreases by 50 percent, and the number of 15-inch laptops sold triples. If the store sells 600 laptops per week during the holiday season, how many more 15-inch laptops than 13-inch laptops are sold?

A. 100
B. 150
C. 200
D. 300
E. 400

The OA is D.

Can any expert explain this PS question please? Thanks.

During a TYPICAL week, the store sells two 13-inch laptops for every 15-inch laptop.
Let x = the number of 15-inch laptops TYPICALLY sold each week
So, 2x = the number of 13-inch laptops TYPICALLY sold each week

However, during the HOLIDAY season, the number of 13-inch laptops sold decreases by 50 percent, and the number of 15-inch laptops sold triples.
So, 50% of 2x = the number of 13-inch laptops sold each week during the HOLIDAYS
In other words, x = the number of 13-inch laptops sold each week during the HOLIDAYS

Also, (3)(x) = = the number of 15-inch laptops sold each week during the HOLIDAYS

If the store sells 600 laptops per week during the holiday season...
We can write: x + (3)(x) = 600
Simplify: 4x = 600
Solve: x = 150

Since x = the number of 13-inch laptops sold each week during the HOLIDAYS, we know that 150 13-inch laptops were sold each week during the HOLIDAYS
600 - 150 = 450, so 450 15-inch laptops were sold each week during the HOLIDAYS

....how many more 15-inch laptops than 13-inch laptops are sold?
450 - 150 = 300

Answer: D

Cheers,
Brent