Problema Solution
In a running and swimming race the athletes must run 2 miles and swim
1 mile. It took Peggy 42 minutes to do this, but if she were able to run
the total 3 miles, it would of taken only 18 minutes. At what rate did swim the mile.
Answer provided by our tutors
let
v = the running rate of Peggy
s = the swimming rate of Peggy
42 min = 42/60 h = 0.7 h
since speed = distance / time => time = distance/speed
2/v + 1/s = 0.7
she runs 3 miles for 18 min = 0.3 h
3/v = 0.3 => v = 3/0.3
v = 10 mph
by plugging the value for v and solving the equation
2/v + 1/s = 0.7
2/10 + 1/s = 0.7
we find
s = 2 mph
to see the step by step solution click here:
Peggy swam at a rate of 2 mph.