A boat traveled upstream \(90\) miles at an average speed of \(v-3\) miles per hour and then traveled the same distance downstream at an average speed of \(v+3\) miles per hour. If the trip upstream took a half-hour longer than the trip downstream, then how many hours did it take the boat to travel downstream?
A. 2.5
B. 2.4
C. 2.3
D. 2.2
E. 2.1
Answer: A
Source: GMAT Prep
A boat traveled upstream \(90\) miles at an average speed of \(v-3\) miles per hour and then traveled the same distance
This topic has expert replies
-
- Legendary Member
- Posts: 1622
- Joined: Thu Mar 01, 2018 7:22 am
- Followed by:2 members
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
I like to begin with a "word equation."Gmat_mission wrote: ↑Sun Apr 11, 2021 3:13 amA boat traveled upstream \(90\) miles at an average speed of \(v-3\) miles per hour and then traveled the same distance downstream at an average speed of \(v+3\) miles per hour. If the trip upstream took a half-hour longer than the trip downstream, then how many hours did it take the boat to travel downstream?
A. 2.5
B. 2.4
C. 2.3
D. 2.2
E. 2.1
Answer: A
Source: GMAT Prep
We can write:
travel time upstream = travel time downstream + 1/2
Time = distance/rate
So, we can replace elements in our word equation to get:
90/(v-3) = 90/(v+3) + 1/2
Now solve for v (lots of work here)
.
.
.
v = 33
So, travel time downstream = 90/(v+3)
= 90/(33+3)
= 90/36
= 5/2
= 2 1/2 hours
Answer: A
Cheers,
Brent