Aman is running through a train tunnel. when he is $\frac{2}{5}$ of the way through, he hears a train that is approaching the tunnel from behind him at the speed of 60 mph. whether he runs ahead or runs back, he will reach an end of the tunnel at the same time the train reaches that end. at what rate, in miles per hour, is he running

36 miles per hour

Explanation:

Since the man has covered 2/5 of the tunnel, he still has 3/5 of the tunnel to go. If he runs ahead, the time it takes for him to cover 3/5 of the tunnel is the same time it takes for the train to cover the whole tunnel (5/5)

In order words, his speed is 3/5 of the train speed.

So the rate, in miles per hour that he is running, is:

60 * 3/5 = 36 miles per hour

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures