Quant Problems

Problem Solving — algebra and arithmetic (GMAT Focus Edition)
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Quant Problems

by sukh » Sun Jul 24, 2011 3:55 am
If a motorist had driven 1 hour longer on a certain day and at average rate of 5 miles per hour faster , he would have covered 70 more miles than he actually did. How many more miles would he covered than he actually did if he had driven 2 hour longer and at an average of 10 miles per hour faster on that day ? a) 100 b) 120 c) 140 d) 150 e) 160

The outside of a soup can has diameter 6.5 centimeters and height 10 centimeters. The inside dimensions of a carton are 26 centimeters by 39 centimeters by 10 centimeters . At most how many soup cans will fit completely inside the carton ? Answer is 24 should not it be 8 owing to pi in calculating volume of soup can
Source: — Quantitative Reasoning |

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by knight247 » Sun Jul 24, 2011 5:29 am
1
Let the actual distance he traveled be d
Let the actual speed be s
Let the actual time be t

d=st.......(1)

Now from 1st condition,
if speed was s+10, time was t+1 then distance he traveled would have been d+70
As per formula we can write this as

d+70=(s+10)(t+1) (Distance=Speed*Time)
Solving we get

5t+s=65........(2)

from condition 2
if speed was s+10, time was t+2, then how much more distance would he have covered than he actually did. Actual distance covered is d. So let the additional distance covered be x. Hence, total distance covered is d+x.

d+x=(s+10)(t+2) (Distance=Speed*Time)
Solving we get,
x-20=10t+2s
x-20=2(5t+s)
x-20=2(65) from (2)
x=150 hence D