Question

a motor car start with a speed of 70 km per hour with its speed increasing every 2 hour by 10 km per hour in how many hours will it cover 345 km

Answer 1

Answer:

4.5 hours

explanation ->

speed for 1st hour = 70 km/h (increases every 2 hour by 10km)

after 2 hours ->

distance travelled  =2 x 70 = 140 km

new speed = 80 km/h

after 4 hours ->

distance travelled 140 + 2x80 = 300km

new speed = 90km/h

time taken with new speed to travel 45 km = 0.5 hour

Hence time taken to travel  345km = (4 + 0.5) = 4.5 hours

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.