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Bunuel
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

It's D. 300.

300 15-inch laptops will be sold more than 13-inch laptops if the store sells 600 laptops per week during the holiday season.
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Initial ratio of 13 and 15 inches: 2: 1

Holiday ratio: 1 : 3

Total : 600 sold: 150 : 450

Difference: 450 - 150 = 300

Answer D
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BrentGMATPrepNow
Bunuel
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

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

Hi BrentGMATPrepNow, when I assign S= 13 inches and L=15 inches > 2S = L
After 50% drop S=3L

S+L = 600
3L+L=600
L=150 , S=450

My confusion is why am I getting opposite result of L & S here?
Thanks Brent
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Kimberly77
Hi BrentGMATPrepNow, when I assign S= 13 inches and L=15 inches > 2S = L
After 50% drop S=3L

S+L = 600
3L+L=600
L=150 , S=450

My confusion is why am I getting opposite result of L & S here?
Thanks Brent

Given: During a TYPICAL week, the store sells two 13-inch laptops for every 15-inch laptop.
Your equation, 2S = L, doesn't meet the given conditions.
For example, S = 5 and L = 10 is a solution to your equation, but S = 5 and L = 10 doesn't satisfy the condition that the store sells two 13-inch laptops for every 15-inch laptop
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Kimberly77
Hi BrentGMATPrepNow, when I assign S= 13 inches and L=15 inches > 2S = L
After 50% drop S=3L

S+L = 600
3L+L=600
L=150 , S=450

My confusion is why am I getting opposite result of L & S here?
Thanks Brent

Given: During a TYPICAL week, the store sells two 13-inch laptops for every 15-inch laptop.
Your equation, 2S = L, doesn't meet the given conditions.
For example, S = 5 and L = 10 is a solution to your equation, but S = 5 and L = 10 doesn't satisfy the condition that the store sells two 13-inch laptops for every 15-inch laptop

Thanks Brent BrentGMATPrepNow, not sure that I quite get it as if S = 5 and L = 10, then 2S = L > 2(5) = 10 ?
Or should it be S=2L then 50% sales drop of S will become 1/2?
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