Aashish94
Bunuel
imhimanshu
Hello Bunuel,
Sorry, but I dont understand the solution.
I thought,since it is given that the dimensions have at most an error of 1 cm. So maximum possible difference in volume would be: (201* 201 * 301) - (200 *200*300). Pls suggest what i am doing wrong.
Posted from my mobile device
Yes, that's correct. But the way I suggested gives and approximate answer which is much easier to calculate than (201*201*301) - (200*200*300)= 160,701.
I have a doubt:
Why it's +1, why it can't be 200-1, 200-1 & 300-1 as the question says the error is almost 1 cm? if we assume 199 199 & 299, the answer will be around 240,000, which is an option (wrong) on the Official GMAT Mock?
Iotaa200*200*300 = 12,000,000
199*199*200 = 11,840,699
Difference = 159,301
I like the percent difference approach.
1 is 0.5% of 200 and 0.333% of 300.
We are increasing (or decreasing!) two dimensions by 0.5% and one dimension by 0.333%. The only reason the difference between increasing and decreasing would be large is if the compounding effects of these changes (that is, where two or more of them overlap) is large compared to the overall. We are talking about very small overlaps compared to the overall, so lets ignore that compounding effect.
0.5% + 0.5% + 0.333% = 1.333%
1% of 12,000,000 = 120,000
0.333% of 12,000,000 = 40,000
1.333% of 12,000,000 = 160,000
Answer choice C.