Question

A car travelling with 5/7 of its usual speed cover 42 km in 1 hour 40 min 48 sec. What is the usual speed

Answer 1

Answer:

Usual speed will be = 35km/hr

Step-by-step explanation:

This is a bit logical question.

I wont use x method to solve this question.

use units method instead

Suppose usual speed of car be 7 units

car is travelling at 5/7 of usual speed

car is travelling at 5 units

convert 1 hr 40 min and 48 sec into hr this will be equal to

(1+40/60+48/60*60)hrs This will be the toal time in hrs

Total time will be 126/75 hrs

now according to question

5units=42(total distance)/126/75(Total time taken)

we get 5units=25km/hr

This means right now the car is travelling at 25 km/hr

1unit= 5km/hr

7 units = 5*7 (km/hr)

7units=35 km/hr ( this will be the usual speed of the car).