Question

A car covers the first half of the distance between two towns at a speed of 45 km/h

and the other half at 55 km/h. Then its average speed is ________.

A. 50 km/h

B. 49.5 km/h

C. 48 km/h

D. 47.5 km/h​

Answer 1

Answer:

49.5 km/h

Explanation:

Average speed is V = distance / time

If a car travels first half is V1 and second half is V2 , then

V = 2× V1 ×V2/V1+V2

= 2×45×55/45+55

= 49.5km/h

Answer 2

Answer

(b) 49.5

Explanation

T1 = x/2*45 = x/90

T2 = x/2*55 = x/110

Time taken = t = t1 + t2

                   = t = x/90 + x/110

                    = t = 90x + 110x/9900

                    = 200/9900

                   = 49.5