Question

Question
A train travels 40 km at a uniform speed of 30 km/h its average speed after travelling another 40 km is 45 km/h for the whole journey, its speed in the second half of the journey is
a.45 km/h
b.90 km/h
c.60km/hr
d.30km/h​

Answer 1

Answer:

90

Explanation:

Given:

Total distance =80km

Average speed of entire journey=45km/h

Total Time taken =total distance/average speed

=80/45 hour

Case :1

Let us CALCULATE time taken to cover first 40km

Speed=30km/h

Distance=40km

T=distance/ speed=40/30

=4/3 hr -----equation ( 1)

Case: 2

Let us CALCULATE time taken to travel next 40km

Let speed be =Xkm/ h

X=40KM/t

t=40/X hours ----equation( 2)

Total time = add equation 1 and 2

=4/3 +40/x

Since total time =80/45 hr

80/45=4/3+40/x

80/45=4x+120/3x

3x(80)=45(4x+120)

80x=15(4x+120)

80x=60x+15*120

20x=15*120

x=15*120/20

X=90km/hr

Therefore bus should travel next 40km distance at a speed of 90 km/h

Answer 2

If RBCs are removed from the body then the oxygen will not be transported to the body and which would creat a deficiency of oxygen in the body which ultimately leads to death...