Question

A motor car starts with the speed of 70 km/hr with its speed increasing every two hours by 10km/hr. in how many hours will it cover 345 kms

Answer 1

Distance covered in first 2 hours = (70 x 2) km = 140 km
Distance covered in next 2 hours = (80 x 2) km = 160 km
Remaining distance = 345 – (140 + 160) = 45 km.
Speed in the fifth hour = 90 km/hr
Time taken to cover 45 km =(45/90) hr = (1/2) hr
Therefore Total time taken = 2 + 2 + (1/2) = 4 (1/2)hrs
that's the answer hope it helps you

Answer 2

Answer:

(e) None of these

Step-by-step explanation:

To find -

Find time ,

Solution :-

Starting speed = 70 km/hr

In first two hours it is = 140 km

For next two hours ,

Speed increased 10 km/hr

→ 70 + 10 = 80 km/hr

For two hours = 80 km

Hence,

Total distance now = 140 +160 = 300 km

Hence,In time of 4 hours it covers 300 km.

Now speed is 90 km/hr

It will take in half hour 45 km remaining to covers it 90 km/hr

Hence ,

It need 4 hours 30 minutes to covers 345 km.