Answer:
One way to do this would be:
1 m = 39.37 in = 39.39 in / 12 in/ft = 3.28 ft
400 m / 65 sec = 6.15 m/sec her running rate
6.15 m/sec * 3.28 ft/m = 20.2 ft/sec
A handy conversion factor is 60 mph = 88 ft/sec
So her speed is 20.2 / 88 * 60 = 13.8 mph
Another way is
400 m * 3.28 ft/m = 1312 ft
1312 ft/65 sec = 20.2 ft/sec
Again using the handy conversion factor
v = 20.2 ft/sec / 88 ft/sec = .229
Since we know that 88 ft/sec = 60 mph
her speed is .229 * 60 mph = 13.8 mph