Speed = Distance / time
v = s / t
In this case s = the distance for her house to the lake.
v1 = s / t1
She walked to the lake at a rate of 4 mph so:
v1 = s / t1
4 = s / t1
Multiply both sides by t1
4 t1 = s
Divide both sides by 4
t1 = s / 4
She walked back at a rate of 2mph so:
v2 = s / t2
2 = s / t2
Multiply both sides by t2
2 t2 = s
Divide both sides by 2
t2 = s / 2
Sally spent 6 hours walking from her house to the lake and back mean:
t1 + t2 = 6
s / 4 + s / 2 = 6
s / 4 + 2 s / 4 = 6
3 s / 4 = 6
Multiply both sides by 4
3 s = 24
Divide both sides by 3
s = 8
The distance for her house to the lake = 8 miles
Proof:
v1 = s / t1
t1 = s / v1
t1 = 8 / 4
t1 = 2 h
v2 = s / t2
t2 = s / v2
t2 = 8 / 2
t2 = 4 h
t1 + t2 = 2 h + 4 h = 6 h
Sally spent 6 hours walking from her house to the lake and back. She walked to the lake at a rate of 4mph and walked back at a rate of 2mph. What is the distance for her house to the lake?
1 answer
1 answer