At noon Joyce drove to the lake at 30 miles per hour, but she made the long walk back home at 4
miles per hour. How long did she walk if she was gone for 17 hours? How far did she walk?
Solution
You know that d=v*t, where d is the distance and v is the speed and t is the time, the proble give
you two speeds and the total time.
Lets call t1 the time that it take her to go from his house to the lake, and lets call t2 the time that
it take her to go from the lake to his house. The distance from his house to the lake is constant, I
mean that the distance does not change. Now lets call v1 the speed of 30mph and v2 the speed of
4mph. The time t is equalt to t=d/v distance divede by speed. Now I hope that you understand the
following equation:
d/v1+d/v2=t The sum of the time that take her to go to the lake from his house and the time that
take her to go from the lake to his house it is the total time. Now we only have to use the given
data.
v1=30mph
v2=4mph
t=17hours
d/30+d/4=17 Now we only have to solve this equation to know the total distance that she
travelled.
2d+15d=1020
17d=1020
d=60 miles she travelled, and therefore the distance from his house to the lake is 30 miles..
At noon Joyce drove to the lake at 30 miles per hour, but she made t.pdf
1. At noon Joyce drove to the lake at 30 miles per hour, but she made the long walk back home at 4
miles per hour. How long did she walk if she was gone for 17 hours? How far did she walk?
Solution
You know that d=v*t, where d is the distance and v is the speed and t is the time, the proble give
you two speeds and the total time.
Lets call t1 the time that it take her to go from his house to the lake, and lets call t2 the time that
it take her to go from the lake to his house. The distance from his house to the lake is constant, I
mean that the distance does not change. Now lets call v1 the speed of 30mph and v2 the speed of
4mph. The time t is equalt to t=d/v distance divede by speed. Now I hope that you understand the
following equation:
d/v1+d/v2=t The sum of the time that take her to go to the lake from his house and the time that
take her to go from the lake to his house it is the total time. Now we only have to use the given
data.
v1=30mph
v2=4mph
t=17hours
d/30+d/4=17 Now we only have to solve this equation to know the total distance that she
travelled.
2d+15d=1020
17d=1020
d=60 miles she travelled, and therefore the distance from his house to the lake is 30 miles.
