Question

4. A truck covers a distance of 150 km at a certain
average speed and then covers another 200 km at
average speed which is 20 km per hour more than
the first speed. If the truck covers the total distance
in 5 hours, find the first speed of the truck.​

Answer 1

Answer:

First speed = 16.67 m/s (approx.)

Step-by-step explanation:

s = (150+200) km = 350,000 m

If first speed = v1

second speed, v2 = (v1 + 5.56) m/s [ 20 km = 5.56 m/s ]

Average speed, v = (v1 + v2)/2 = v1 + 2.78 m/s

t = 18, 000 sec

Now,

s = vt

=> 350,000 = (v1 + 2.78) * 18,000

=> v1 = 16.67 m/s

Answer 2

Answer:

Step-by-step explanation:

Question :-

A truck covers a distance of 150 km at a certain average speed and then covers another 200 km at an average speed which is 20 km per hour more than the first speed. if the truck covers the total distance in 5 hours, find the first speed of the truck.

Answer :-

Solution :-

Let the first speed of truck be x km/h.

According to the Question,

Then, 150/x + 200/x + 20 = 5

⇒ 150 + 300 + 200x = 5x(x + 20)

⇒ x² - 50x - 600 = 0

⇒ x² - 60x + 10x - 600 = 0

⇒ x(x - 60) + 10(x - 60) = 0

⇒ (x - 60) (x + 10) = 0

⇒ x = 60, - 10 (As speed cannot be negative)

⇒ x = 60 km/h

Hence, the first speed of the truck is 60 km/h.​