Time and Distance Practice Test 4 with solutions

Question : 26 of 38

Marks: +1, -0

The distance of Dr Akhil’s clinic to home is 120 km. One day, he was late by an hour due to emergency than the normal time to leave for home. So, he increased his speed by 20 km/hr and thus he reached home in the normal time. What is the increase in speed of Dr Akhil?

70 km/hr
60 km/hr
42 km/hr
55 km/hr
None of these

Validate

Solution:

Let the speed = x km/hour
According to the question,

{120}/x-{120}/{x+20}

= 1

{x+20-x}/{x^2+20x}

1/{120}

x^2

+ 20x - 2,400 = 0

x^2

+ 60x - 40x - 2,400 = 0
(x + 60) (x - 40) = 0
⇒ x = 40 km/hour
Increased speed = 40 + 20 = 60 km/hour

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