Question

journey
10. (1) A train covers a distance of 670 km in 6 h 5 min. If it covers the first 390 km of the
journey at 90 km/h, find its speed for the rest of the journey.
(1) A bus covers 630 km in 9 h. If it completes the first two thirds of the journey at
60 km/h, calculate its speed for the rest of the journey.
ndoto​

Answer 1

Answer:

Step-by-step explanation:

Total distance travelled by train = 670 km

Time taken to travel 670 km = 6 hr 5 min = begin mathsize 12px style 6 5 over 60 space h r space equals space 6 1 over 12 h r space equals space 73 over 12 space h r end style

If first 390 km is travelled by 90 km/hr speed,  then time taken = 390/90 = 13/3 hr.

 

Time left  to travel remaining distance 280 km = begin mathsize 12px style 73 over 12 space minus space 13 over 3 space equals space 73 over 12 minus space 52 over 12 space equals space 21 over 12 space space equals space 7 over 4 h r end style

required speed = begin mathsize 12px style fraction numerator 280 space space space over denominator begin display style bevelled 7 over 4 end style end fraction space space equals space 160 space k m divided by h r end style

Answer 2

Answer:

Total distance is 670 km

Total time is (6+5/60)hr

= (6+5/12)hr

= 73/12 hr

Then 1st case

distance is 390 km

Speed is 90km/h

Then time will be 390/90

= 13/2

2nd case for the rest of the journey.

Distance will be 670 - 390 is 280km

Time will be (73/12) - (13/3)

= (73-52)

= 7/4hr

Then speed for the rest of the journey will be distance by time

=> 280 x 7/4

=> (280 x 4/7)

=> 160km/h

I hope this will be help you.