devansh1496 wrote:
Could someone tell me if the following approach is valid? I got the answer via plugging in, but if there are any fallacies in my approach please do point them out.
I decided to plug in the answers and try it out. If she planned to read 90 pages a day, that would mean that would mean that the total number of pages should be cleanly divisible by 90.
Second, the difference between the total pages and the pages left, i.e. the pages she read, should be divisible by 75(it has been given that she at first read 75 pages/day)
Plugging in 15 does not work.
Plugging in 16 gives us 16*90 = 1440 total pages she wanted to read in 16 days.
Subtracting 690, that is, the number of pages left from 1440 gives us the number of pages she read in the first how-many-ever days, i.e. 1440-690 = 750.
If she read 75 pages per day, the number we got above should be divisible by 75, and 750 is divisible by 75!
Voila! She had 16 days to complete her assignment.
Hi devansh1496,
To answer your immediate question: Your approach here is great (and a perfect example of how strategic thinking - in this case, TESTing THE ANSWERS - can turn certain types of story problems into simple Arithmetic)!
GMAT assassins aren't born, they're made,
Rich
Contact Rich at: Rich.C@empowergmat.com