Question

a car cover 30 kilometre at a uniform speed of 30 km per hour what would be its speed for the next 90km if the average speed the entire journey is 60 km/h

Answer 1

Hi ...

Given: total distance= 120 km

Avg. Speed = 60 km/h

Time taken by car to cover 30 km= 30/30= 1 hr

Let the speed of car for next 90km be x

So, the time taken to complete 90 h = 90/x

Now, Avg. Speed = total distance/ total time taken

60 = 120/(1+(90/x))

60(x+90)= 120x

60x + 5400 = 120x

60x = 5400

x = 90 km/h (speed for next 90 km) .

Hope this helps u!

Answer 2

$\boxed { \bf Hello \: there}$

•Given :-

• Total Distance , d = 30+90 km = 120km

• Average speed , Vavg = 60 km/h

• Total time = 2h

• Let the next speed be x
then average speed = (30+ x )km/h
$we \: know \rightarrow \\ \\ \boxed{average \: speed \: = \frac{total \: distance \: travelled}{total \: time \: taken} }$
Distance = Average speed × Time

=> 120 = [ (30+ x )/2 ]×2

=> x = 90 km /h


Hence the speed should be 90km/h


Hope this helps you ☺