alex.gellatly wrote:At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours at 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A) 3/25
B) 11/36
C) 7/12
D) 2/3
E) 25/36
So far, the posts have used the ratio (consumption)/(distance traveled).
We can also use the ratio (consumption)/(time elapsed).
At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles.
Time = distance/speed
So, time to travel 30 miles = 30/50 =
3/5 hours.
This means that the car uses
1 gallon for every
3/5 hours.
Let
x = the number of gallons of gas used during the
5 hour trip.
We get the following equivalent ratios:
1/(
3/5) =
x/
5
Cross multiply to get: 5 = (3/5)x
Multiply both sides by 5/3 to get: 25/3 = x
So, the car uses
25/3 gallons of gas
The amount of gasoline used would be what fraction of a full tank?
We get (
25/3)/12, which equals [spoiler]25/36[/spoiler]
Answer:
E
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
