Question

A race car completes a lap on a 1600 m long track with an average speed of 250 km/h. If the car's average speed on the first half of the track was 210 km/h, what was its average speed (in km/h) on the second half? km/h

Answer 1

Answer: 295km/h  

Explanation: 250 = (205+x)\2  

                     2*250 = 205+x  

                    500 = 205+x  

                    500-205 = x  

                    295 = x

Answer 2

A race car completes a lap on a 1600 m long track with an average speed of 250 km/h. If the car's average speed on the first half of the track was 210 km/h, 290 km/hr was its average speed on the second half.

Explanation:

The car in order to complete the race of 1600 m took an average speed of 250 km/ hr. given that the average speed of first half of the race was 210 km/hr. The second half average speed can be calculated as per the following method,

Given that total average speed of the car in race=250 km/hr.

Average speed in first half of race= 210 km/hr.

As we know that,

average speed = $\frac{f \text {irst half of average speed}+\text {second half of average speed}}{2}$

Thereby, we have,

 $250=\frac{210+\text {average speed of second half of race}}{2}$

               $250 \times 2=210+\text {average speed of second half of race}$

               $\text { average speed of second half of race }=500-210=290 \text { km/hr }$