SIR ANSWER THIS

Asked by theprincess | 22nd Feb, 2010, 07:25: PM

Expert Answer:

In 2 hrs, A travels 24 km, hence his speed is 24/2 = 12 km/hr.

And if the speed of B is VB, then

2VB + 24 = PQ

B travels for some time T, a distance of 24 km to reach P.

T = 24/VB,

and in the same time T, A travels 2VB but 20 km short.

T = (2VB - 20)/VA = (2VB - 20)/12

Since the time is same,

24/VB = (2VB - 20)/12

2VB2 - 20VB - 288 = 0

VB2 - 10VB - 144 = 0

VB2 - 18VB + 8VB - 144 = 0

(VB + 8)(VB - 18) = 0

VB = 18 km/hr

PQ = 24 + 18x2 = 60 km.

Regards,

Team,

TopperLearning.

 

Answered by  | 24th Feb, 2010, 07:06: AM

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