Alice and Bob traveled in the same direction along the same

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Max@Math Revolution: Elite Legendary Member; Posts: 3991; Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members; Location: Las Vegas, USA; Thanked: 19 times

by Max@Math Revolution » Wed Mar 21, 2018 1:45 am

[GMAT math practice question]

Alice and Bob traveled in the same direction along the same route at their respective constant speeds of 12 km per hour and 6 km per hour. They each started to travel from their own houses. Bob’s house is halfway between Alice’s house and the destination. After passing Bob, Alice took 10 minutes to reach the destination. How many minutes did it take Bob to reach the destination after Alice passed him?

A. 5 min
B. 6 min
C. 8 min
D. 10 min
E. 20 min

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Source: Beat The GMAT — Problem Solving | Wed Mar 21, 2018 1:45 am

swerve: Legendary Member; Posts: 2604; Joined: Sun Oct 29, 2017 2:04 pmFollowed by: 6 members

by swerve » Wed Mar 21, 2018 9:42 am

Hi Max@Math Revolution,

Since the speed of Alice is double the speed of Bob the time taken by Alice is half the time taken by Bob.

Alice takes 10 mins thus Bob takes 10/(1/2) = 10*2 = 20. Option E.

Regards!

Max@Math Revolution: Elite Legendary Member; Posts: 3991; Joined: Fri Jul 24, 2015 2:28 amFollowed by: 37 members; Location: Las Vegas, USA; Thanked: 19 times

by Max@Math Revolution » Thu Mar 22, 2018 11:15 pm

=>

After Alice passed Bob, she traveled for 10 more minutes.
Since Bob’s speed is half of Alice’s speed, he took a further 20 minutes to reach the destination.

Therefore, the answer is E.

Answer: E

deloitte247: Legendary Member; Posts: 2214; Joined: Fri Mar 02, 2018 2:22 pmFollowed by: 5 members

by deloitte247 » Sat Mar 24, 2018 11:19 am

Alice speed speed= 12km/hr
Bob speed= 6km/hr

Alice speed is twice the speed of Bob and the time taken by Alice will be 1/2 of the time taken by Bob.
After passing Bob, Alice took 10 minutes to reach the destination.
Bob now takes $$\frac{\left(10\right)}{\frac{1}{2}}$$ = 10*2=20 minutes

Therefore, it took Bob 20 minutes to reach the destination after Alice passed him.
Hence, option E is accurate

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