Esther drove to work in the morning at an average speed of 45 miles per hour. She retruned home in the evening along the same route and averaged 30 miles per hour. If Esther spent a total of one hour communting to and from work, how many miles did Esther dirve to work in the morning?
I don't know, but the answer's supposed to be 18 somehow?
2007-07-21 14:47:42 · 4 answers · asked by Team_Balla 3 in Science & Mathematics ➔ Mathematics
I know that!!! I just need it explained to me!
2007-07-21 14:52:45 · update #1
Esther drove x miles @ 45 miles per hour in the morning.
Esther drove x miles @ 30 miles per hour in the evening.
So the drive in the morning took x/45 hours.
The drive in the evening took x/30 hours.
This is because time = distance / speed.
So we know that
x/45 + x/30 = 1
multiplying everything by 90, we get:
2x + 3x = 90
5x = 90 (combine the like terms)
x = 18 miles. (divide both sides by 5)
2007-07-21 14:58:21 · answer #1 · answered by Anonymous · 0⤊ 1⤋
Miles per hour-ex. If you're going 5 mph, in an hour you will have went five miles. So 1/2 an hour in the morning means 45 divided by 2= 22 1/2. Half an hour in the evening means 30 divided by 2=15. So 22 1/2 + 15= 37 1/2 divided by 2 = 18 1/2 r 1
Answer: 18 1/2 r 1
2007-07-21 15:03:59 · answer #2 · answered by rocketboy 2 · 0⤊ 1⤋
t1=d/r = d/45 going
t2 = d/r =d/30 returning
t1+t2 = 1= d/45+d/30
1 = (2d+3d)/90 = 5d/90 = d/18
d = 18 miles
2007-07-21 14:57:25 · answer #3 · answered by ironduke8159 7 · 1⤊ 0⤋
yup its 18
2007-07-21 14:51:21 · answer #4 · answered by Anonymous · 0⤊ 1⤋