A car travelling with 5/7 of its actual speed covers 42 km in 1 hr 40 min 48 sec find actual speed car

Question

A car travelling with 5/7 of its actual speed covers 42 km in 1 hr 40 min 48 sec find actual speed car

 

 

i know the solution what i need to find out that

how to convert time in to fraction

1hr 40 min 48sec

                                                          48                4

now i know converting minute to sec 40 60  that is 40 5

 

                                                                                  51    

after that i did get for hours calculation in book that is  1  75

how that come from

 

Answer 1

1 hr = 60 min

 

1 min = 60 secs

 

So start with 48 secs first which is 48/60 min = 0.8 min

 

Now, it is 1 hr 40.8 min.

 

40.8/60 = 0.68 hr

 

So the time covered is 1.68 hrs.

 

speed = distance/time

 

(5/7)*actual speed = 42 km / 1.68 hr

 

(5/7)*actual speed = 25

 

actual speed = 25*(7/5) = 35 km/hr