Nine men went to a restaurant. Eight of them spent $6 each for their meals and the ninth man spent $4 more than the average expenditure of all nine men. What is the average expenditure?
The Usual Method
Total money spent by eight men = 6 x 8 = $48.00
Total money spent by 9 men = 48 + (x + 4), where ‘x’ is the average spend of all nine men.
Total money spent can also be written as = 9x
This can be equated to 48 + (x + 4).
Hence average = $6.50
Estimated Time to arrive at the answer = 45 seconds.
If 8 men out of 9 men spent $ 6 each, assume the average to be $6.
We also know that the 9th man spent $ 4 more than the rest. This $4 has to be apportioned to the 8 men who spent $6 each. Hence, has to be added to the original spent of $6. i.e 60 + 0.50 = $6.50 which is the new average.
Estimated Time to arrive at the answer = 15 seconds.