Eleven years ago Tina was half as old as Ike will be in 4 years.

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BTGModeratorVI: Legendary Member; Posts: 1223; Joined: Sat Feb 15, 2020 2:23 pmFollowed by: 1 member

by BTGModeratorVI » Fri May 29, 2020 6:45 am

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Eleven years ago Tina was half as old as Ike will be in 4 years. If Ike is m years old now, how old is Tina now, in terms of m?

A. 4m - 11
B. m/2 + 13
C. 1/(2m - 22)
D. (4m + 11)/2
E. 2m-7

Answer: B
Source: Economist GMAT

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Re: Eleven years ago Tina was half as old as Ike will be in 4 years.

by Brent@GMATPrepNow » Sat May 30, 2020 6:33 am

BTGModeratorVI wrote: ↑
Fri May 29, 2020 6:45 am
Eleven years ago Tina was half as old as Ike will be in 4 years. If Ike is m years old now, how old is Tina now, in terms of m?

A. 4m - 11
B. m/2 + 13
C. 1/(2m - 22)
D. (4m + 11)/2
E. 2m-7

Answer: B
Source: Economist GMAT

Given: m = Ike's PRESENT age
So, m + 4 = Ike's age IN 4 YEARS
So, (1/2)(m + 4) = Tina's age 11 YEARS AGO
So, (1/2)(m + 4) + 11 = Tina's PRESENT age

The answer does not appear among the answer choices. So, we'll need to SIMPLIFY the expression
Take: (1/2)(m + 4) + 11
Expand: m/2 + 2 + 11
Simplify: m/2 + 13

Answer: B

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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ezmodest: Newbie | Next Rank: 10 Posts; Posts: 6; Joined: Sat May 30, 2020 9:02 am

Re: Eleven years ago Tina was half as old as Ike will be in 4 years.

by ezmodest » Sat May 30, 2020 9:10 am

This is how I approached it:

m = Ike's age
t = tina's age

The statement says that eleven years ago Tina was half of Ike's age four years from now. If you're having a hard time understanding this, just imagine that eleven years ago Tina was 10 and four years from now Ike is 20. Therefore we know that:

2*(t-11) = m+4
t = (m+4)/2 +11
t = m/2 + 2 + 11
t = m/2 + 13

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dkimb270: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Sat May 30, 2020 12:36 pm

Re: Eleven years ago Tina was half as old as Ike will be in 4 years.

by dkimb270 » Sat May 30, 2020 12:44 pm

Easy problem to tackle, guys!

Start by assigning a variable to represent Ike's present age. The problem calls it M.
Next, we want to figure out Ike's age four years from now: M + 4 = Ike's age four years from now.
Ike's age four years from now is twice Tina's age eleven years ago. To put it mathematically, 0.5(M + 4) = Tina's age eleven years ago.
Finally, we need to get back to Tina's present age: 0.5(M + 4) + 11 = Tina's present age.
If we simplify:
Step 1: 0.5(M + 4) + 11 = Tina's present age
Step 2: 0.5M + 2 + 11 = Tina's present age
Step 3: 0.5M + 13 = Tina's present age --> this is B!

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

Re: Eleven years ago Tina was half as old as Ike will be in 4 years.

by deloitte247 » Fri Jun 05, 2020 1:33 am

Let Ike's present age = m
Therefore, m + 4 = Ike's age in 4 years

Tina's age 11 years ago = 1/2(m + 4)
Tina's present age = 1/2(m + 4 ) + 11

$$=\frac{\left(m+4\right)}{2}+\frac{11}{1}$$
$$\frac{m}{2}+\frac{4}{2}+\frac{11}{1}$$
$$\left(\frac{m}{2}\right)+\left(\frac{2}{1}+\frac{11}{1}\right)$$
$$=\frac{m}{2}+13$$

Answer = B

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