Smarter way to resolve?
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
Is there any better way than using the equation? Backsolving, PoE? Please suggest.
yes, we can do the backsolving here.
One thing, to note from this question is,
Given downstream and upstream speeds, the difference in their speeds is 6.
Out of the given five answer choices, the best to work on here is 2.5.
Lets say, if the downstream time taken is 2.5hours, given that downstream it travels 90 miles,
So it speed would be 36 miles/ hour.
So this equal to v+3 = 36
So, v = 33
Then the upstream speed is v-3 = 30 miles.
So, if we check 90 / 30 – 90/36 = 2.5
Why I picked answer choice A is? very simple out of the decimals given, thats the best decimal to work out.
So the answer is A.
Hope this helps.
