Time and Distance Practice Test 4 with solutions

Question : 21 of 38

Marks: +1, -0

Two poles P and Q are 720 m apart. Dinesh starts from P and Mahesh starts from Q at the same time. If they run towards each other, they meet in 36 seconds and in case they run towards the same direction they will meet in 3 minutes. Find the speed of the fastest runner.

15 m/sec
10 m/sec
12 m/sec
9 m/sec
$8 1/3$ m/sec

Validate

Solution:

Let the speed of the fastest runner = x and the speed of the slower runner = y
Relative speed (same direction) = x - y
Relative speed (opposite direction) = x + y
According to the question,

{720}/{x+y}

= 36
(x + y) 36 = 720
36x + 36y = 720
⇒ x + y = 20 ……(i)

{720}/{x-y}

= 180 (3 minutes)
x − y
⇒ x - y = 4 ……(ii)
Equating (i) and (ii), we get
x = 8 m/sec and y = 12 m/sec
So, speed of the fastest runner is 12 m/sec

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