Question

Brian drove 120 miles at a speed of 60 mph. He drove the same distance back home at an average speed of 40 mph. Brian adds the speeds and divides by two to come up with an average speed of 50 mph what is wrong with his reasoning? Find his average speed

Answer 1

this is how to find the average speed: the total distance ÷ the total number of hours
the total distance in this case is 120+120=240
the total hours is 120/60 + 120/40 =2+3=5
so 240/5=48
48 miles per hour