Michael earns $6.00 per hour for the first 40 hours he works per week, and twice this rate for overtime. If Michael earned $324 last week, how many hours did he work?

43
44
45
46
47
Source: https://www.freequestionaday.com/gmat

Conventional way [Timetaken > 1 min]
write an equation and solve for x
40 * 6 + 12*X = 324
X=(324 - 240)/12
X=84/12=> 7

Backsolving [Less than 1 min ]
It is best to start with B or D and NOT EXTREMES (A or E).
start with B. 240 + 4*12 = 288 < 324
288 is less than 324 hence jump to D.
240 + 6*12 = 312

D option is still less than 324. You can confidently select E and move to the next question.
This is because options in the GMAT are ALWAYS ordered in ascending order.


GMAT Approach:[less than few seconds]
4 is the units digit in 324.
$12 is the rate paid for the extra hours. 12 * units digits of expected AO = 4 ( as in 324)
3*2=6
4*2=8
5*2=0
6*2=2
7*2=4 [Correct AO]

This is what we should do while preparing for GMAT quant. Identify easier/quicker ways to solve problems and save few seconds on the real test.