Gmat_mission wrote:Tom and Samuel are riding motorcycles down the highway at constant speeds. If Tom is now 2 miles ahead of Samuel, how many minutes before Tom is 3 miles ahead of Samuel?
(1) Tom is traveling at 70 miles per hour and Samuel is traveling at 60 miles per hour.
(2) Tom left 5 minutes before Samuel.
[spoiler]OA=A[/spoiler].
Can any expert explain to me how can I conclude that the statement (2) is not sufficient? Thanks in advanced.
Target question: How many minutes before Tom is 3 miles ahead of Samuel?
Given: Tom is now 2 miles ahead of Samuel
Statement 1: Tom is traveling at 70 miles per hour and Samuel is traveling at 60 miles per hour.
We don't really need to apply answer formulas here. We need only recognize that, IF we were to reenact this scenario,
we would have enough information to answer the
target question
Here's what I mean:
Let's go to a stretch of highway and place Tom 2 miles ahead of Samuel (as is given in the question)
3-2-1.....GO! Tell Tom to drive 70 miles per hour and tell Samuel to drive 60 miles per hour
At the same time, start your stopwatch and observe how many
minutes it takes Tom to be 3 miles ahead of Samuel
As we can see, this experiment would allow us to answer the
target question with certainty
As such, statement 1 is SUFFICIENT
Statement 2: Tom left 5 minutes before Samuel
There are several scenarios that that satisfy statement 2. Here are two:
Case a: Tom's speed is 10 mph and Samuel's speed is 10 mph. In this case,
Tom will NEVER be 3 miles ahead of Samuel
Case b: Tom's speed is 1,000,000,000 mph and Samuel's speed is 1 mph. In this case,
Tom will be 3 miles ahead of Samuel in less than 1 second
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Answer: A
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
