lea drove from A to B at 2/3 of the average speed at which she returned from B to A. What percent of her total driving time did it take Lea to drive from A to B?
2006-10-19 14:23:41 · 8 answers · asked by shishu45 2 in Education & Reference ➔ Homework Help
Be very careful of the other solutions. Everyone else is saying that she spent 2/3 of the time driving from A to B and 1/3 of the time driving from B to A. To do that, she would be driving twice as fact from from B to A as she would be from A to B. They do not take time into consideration.
These problems are easiest to do if you make some assumptions.
To make things easy, let's say that her average driving speed was 60 mph and the towns are located 60 miles apart.
To go from A to B...
She drove 2/3 of the average speed, meaning she drove 40 mph. That means it took her 1.5 hours to get there.
To go from B to A...
She drove 60 mph, meaning that it took her 1 hour to return.
She spent a total of 2.5 hours in the car. Therefore, to drive from A to B, she spent...
1.5/2.5 = 0.6 = 60 percent
She spent 60 percent of her time driving from A to B.
2006-10-19 14:30:22 · answer #1 · answered by Josh 2 · 0⤊ 0⤋
The times involved are t (A to B) + t (B to A) = total time T
t (A to B) = distance traveled / speed (A to B)
t (B to A) = distance traveled / speed (B to A)
speed (A to B) = 2/3 speed (B to A). Since the distance traveled is the same each time and using the two equations above,
t (B to A) = 2/3 t (A to B)
t (A to B) + t (B to A) = total time T
substituting: t (A to B) + 2/3 t (A to B) = T
5/3 t (A to B) = T
t (A to B) = 3/5 T or 60% of the time required
to go from A to B
2006-10-19 21:43:56 · answer #2 · answered by Doug R 5 · 0⤊ 0⤋
percent is based on 100
2/3 of 100 percent ...or her total driving time would be
100 divided by 2/3 ....or 66.6 %
2006-10-19 21:29:01 · answer #3 · answered by ? 6 · 0⤊ 0⤋
2/3 + 3/3 = total time driven. 4/6 = from point a to b. 4/6 = x/100. x = 66.66%
2006-10-19 21:29:17 · answer #4 · answered by mr_director29 2 · 0⤊ 0⤋
60%.
To prove it, try substituting in some numbers to see if they work.
For example:
B to A 30mph, 30 miles, =1hour
therefore:
A to B 20mph, 30miles, =1.5hours
Total time 2,5 hours
1.5/2.5=.6=60%
Edit: I see Josh and I think alike.
2006-10-19 21:34:34 · answer #5 · answered by StormyRidge 2 · 0⤊ 0⤋
66.6% is the answer because when you divide 100 by 2/3 the answer is 66.6
2006-10-19 21:31:03 · answer #6 · answered by Baby Lee 1 · 0⤊ 0⤋
yes, I can.
2006-10-19 21:27:43 · answer #7 · answered by wildstar_2 6 · 0⤊ 0⤋
i think is 66.6%
2006-10-19 21:27:24 · answer #8 · answered by Val 2 · 0⤊ 0⤋