Question

A man drives 180 km from city A to city B in 4 hours 10 minutes and returns to city A in 3 hours 20
minutes Find the average speed of the whole journey.
A train 420 m long is running at a speed of 90 km/hr If it crosses a platform in 45 seconds, find the length​

Answer 1

Answer:

Total distance = 180+180=360 km

Total time 4hr.lOmin+3hr.20 min

= 7 hrs.30 min = 7.5 hrs

Av.speed = 360/7.5=48 km/hr

2) Length of train420m=0.42, km

Length of platform = xkm

Total distance = 0.42+x

Speed=90 km/hr

time=45 Sec=45/3600

(0.42+x)/90=45/3600

(042+x)X3600 = 90x45

0.42+x=9045/36oo=1.125

x = 1.125-0.42

= 0 .705Km

length of platform = 705m