Question

In order to qualify for finals in racing event,a race car must achieve an average speed of 250km/hr on a track with a total length of 1600m.if a particular car covers the first half of the track at an average speed of 230km/hr,what minimum average speed must it have in the second half of the track in order to qualify?

Answer 1

The minimum average speed needed in the second half is 270 km/hr

Explanation

We can divide the track in two parts. For the first half of the track the average speed the car achieved was 230 km/hr and we need to make sure that the average speed of the full track is 250 km/hr. Then, we can calculate the average speed of the two parts of the track and force this to be equal to 250 km/hr. In equation, defining
`v_2` as the average speed of the second half:

`(230 + v_2)/(2)=250`

Solving for
`x`

`x=250*2-230\\x=500-230\\x=270`

Therefore, achieving a speed of 270 km/hr in the second half would be enough to achieve an average speed of 250 on the track.