Today Rebecca, who is 34 years old, and her daughter, who is 8 years

Question

Today Rebecca, who is 34 years old, and her daughter, who is 8 years old, celebrate their birthdays. How many years will pass before Rebecca’s age is twice her daughter’s age?

(A) 10
(B) 14
(C) 18
(D) 22
(E) 26

Kudos for a correct  solution .

goldfinchmonster · Accepted Answer

Ans is c,

Present age is 34 & 8

Add x yrs to both their present ages and form the equation which satisfies the other condition, i.e rebecca's age is twice of her daughters.

( 34 + x ) = 2 ( 8 + x )

X = 18.

paulaalv11 · Answer

For this precise problem of age-doubling, I follow a simple reasoning.

Rebecca is 34 years old and her daughter is 8. Thus they’re 26 years apart from each other. While the daughter is younger than 26, her mom’s age will always more than double hers, whereas when she’s older than 26, the mom’s age will less than double hers. It is precisely at 26 that the daughter’s age will be doubled by her mom.

Why?  
Let  a = number of years Rebecca had lived before the daughter was born
Let  b = number of years Rebecca has lived after her daughter’s birth
Let  c = number of years the daughter has lived (after being born)

We are looking for:
(1)  b - 8 , which will be the solution of the problem.

What the stem tells us is:
(2)  a + b = 2c 
(3)  a = 26

What logic tells us is
(4)  b = c

Thus:
(5)  26 + b = 2b  ->  b = 26

From (1), we get the solution to the problem:   26-8 = 18  
Hope this helps!

MathRevolution · Answer

Forget conventional ways of solving math questions. In PS, IVY approach is the easiest and quickest way to find the answer.

Today Rebecca, who is 34 years old, and her daughter, who is 8 years old, celebrate their birthdays. How many years will pass before Rebecca’s age is twice her daughter’s age?

(A) 10
(B) 14
(C) 18
(D) 22
(E) 26

After x years passes Rebecca’s age will be (34+x) years old, and her daughter’s age will be (8+x) years old. Since the Rebecca’s age is twice her daughter’s age (34+x)= 2 * (8+x) ---> 34+x=16+2x ---> x= 18.

The answer is (C).

Konstantin1983 · Answer

I think that the easiest way to solve this problem is to pick numbers. Start with C. 34+18=52 18+8=26 26*2=52 Bingo!

septwibowo · Answer

- Now, Rebecca is 38 y.o. and her daughter is 8 y.o.
- How many years from now, the ratio between Rebecca's and Daughter's age will be 2:1?
- Let x = number of years
- Solution =  \frac{(34+X)}{(8+X)}  =  \frac{2}{1}  -> we can cross multiply :  34+X=16+2X  -->  -X=-18 , thus  X=18 .

C.

arvind910619 · Answer

Let the number of years be X 
So according to question we have X+34=2*(8+X)
X=18

Sent from my ONE E1003 using  GMAT Club Forum mobile app

nkmungila · Answer

Trail and Error
start with middle
34+18 = 2(8+18)
52 = 2(26)
Correct Answer is C

JeffTargetTestPrep · Answer

We are given that Rebecca is 34 and her daughter is 8. We can let n = the number of years before Rebecca is twice as old as her daughter. At that time, Rebecca will be (34 + n) years old and her daughter will be (8 + n) years old, and Rebecca will be twice her daughter’s age:

34 + n = 2(8 + n)

34 + n = 16 + 2n

18 = n

Answer: C

FANewJersey · Answer

https://i.imgur.com/GeXGIYd.png

Abhishek009 · Answer

34 + t = 2(8 + t)

Or,  34 + t = 16 + 2t

Or,  t = 18  , Answer must be (C)

BrentGMATPrepNow · Answer

STRATEGY : Upon reading any GMAT Problem Solving question, we should always ask,   Can I use the answer choices to my advantage?   
In this case, we can easily test the answer choices. 
From here, I'd typically give myself up to 20 seconds to identify a faster approach, but I can already see that testing the answer choices will be super fast.

GMAT-specific approach  : Test the answer choices
Let's start by testing the middle value (in most cases, it's a good idea to start with the middle value, because you can often eliminate answer choices based on the results of testing choice C)

(C) 18 . This answer suggests that Rebecca will be twice as old as her daughter in 18 years. 
In 18 years, Rebecca's age will = 34 + 18 = 52
In 18 years, the daughter's age will = 8 + 18 = 26
Since 52 = 2 x 26, the correct answer must be C.

Conventional approach  : Apply algebraic techniques
Let x be the number of years from today.
So, x years in the future, Rebecca's age will be  34 + x 
And, x years in the future, her daughter's age will be  8 + x

We want Rebecca’s future age to be twice her daughter’s future age.
We can create the following "word equation":  (Rebecca’s future age) = 2(daughter’s future age) 
Or we can write:  (34 + x) = 2(8 + x) 
Expand to get:  34 + x = 16 + 2x 
Solve to get:  x = 18 
 Answer: C

Cheers,
Brent

Basshead · Answer

My approach when answering these types of problems is working backwards and testing the answer choices.

Let start at B:

34 + 14 = 48 / 14 + 8 = 22. Incorrect

Let's look at C:

18 + 34 = 52 / 8 + 18 = 26. Correct!

Answer is C.

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