manhattan age problem

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resilient: Legendary Member; Posts: 789; Joined: Sun May 06, 2007 1:25 am; Location: Southern California, USA; Thanked: 15 times; Followed by:6 members

manhattan age problem

by resilient » Fri Mar 07, 2008 7:52 pm

jane started baby-sitting when she was 18 yrs old. However, she only baby sat children who were, at most, half her age. Jane is currently 32 eyars old, and she stopped baby sitting 10 yrs ago. What s the current age of the oldest person that Jane could have baby sat?

qa is 23, I got the answer of 21.

Appetite for 700 and I scraped my plate!

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Source: Beat The GMAT — Problem Solving | Fri Mar 07, 2008 7:52 pm

netigen: Legendary Member; Posts: 631; Joined: Mon Feb 18, 2008 11:57 pm; Thanked: 29 times; Followed by:3 members

Re: manhattan age problem

by netigen » Fri Mar 07, 2008 8:53 pm

Enginpasa1 wrote:jane started baby-sitting when she was 18 yrs old. However, she only baby sat children who were, at most, half her age. Jane is currently 32 eyars old, and she stopped baby sitting 10 yrs ago. What s the current age of the oldest person that Jane could have baby sat?

qa is 23, I got the answer of 21.

You will get the answer if you go by her lower age = 18

when she was 18 the kids she baby sat will be 9 or above

So add 14 (32-18) to 9 = 23

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resilient: Legendary Member; Posts: 789; Joined: Sun May 06, 2007 1:25 am; Location: Southern California, USA; Thanked: 15 times; Followed by:6 members

how about this

by resilient » Sat Mar 08, 2008 12:00 am

I see your point. However, I am stuck on the older of the two age groups. What if I add the 14 (32-18) TO THE OLDER age of 11. This yields the answer of 25. I am stuck on that now!

Appetite for 700 and I scraped my plate!

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Stuart@KaplanGMAT: GMAT Instructor; Posts: 3225; Joined: Tue Jan 08, 2008 2:40 pm; Location: Toronto; Thanked: 1710 times; Followed by:614 members; GMAT Score:800

Re: how about this

by Stuart@KaplanGMAT » Sat Mar 08, 2008 7:04 am

Enginpasa1 wrote:I see your point. However, I am stuck on the older of the two age groups. What if I add the 14 (32-18) TO THE OLDER age of 11. This yields the answer of 25. I am stuck on that now!

She was only able to baby sit 11 year olds when she was 22, which is only 10 years ago, so the 11 year olds that she baby sat would only be 11+10 = 21 years old today.

However, she was able to baby sit the 9 year olds when she was 18, which was 14 years ago. If they were 9 years old 14 years ago, they'd be 23 years old today.

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xilef: Master | Next Rank: 500 Posts; Posts: 111; Joined: Thu Jan 31, 2008 4:05 pm; Thanked: 18 times; Followed by:1 members

by xilef » Tue Mar 11, 2008 10:56 am

I understand the question, but it is very tricky, because the first time I read it I understood it as asking for the age of the oldest person at the time of babysitting not the currently oldest person that was babysat by Jane.