Question

A test driver has to drive a car on a 1-mile track for two rounds in a way, that his average speed is 60 mph. On his first round his average speed is 40 mph. How fast does he need to drive, to get the right speed average?

Answer 1

(40+x)/2=60

40 +x = 120

x = 80

check :

40+80 = 120

120/2 = 60

 so his second round needs to be 80 mph