GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 19 Oct 2019, 17:50

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# How old is Robert now? (1) The product of his age now and his age

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 58445
How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

22 Feb 2018, 20:47
00:00

Difficulty:

15% (low)

Question Stats:

79% (01:15) correct 21% (01:24) wrong based on 82 sessions

### HideShow timer Statistics

How old is Robert now?

(1) The product of his age now and his age five years from now is 24.

(2) Six years from now he will be three times as old as he is now.

_________________
Retired Moderator
Joined: 22 Aug 2013
Posts: 1428
Location: India
Re: How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

22 Feb 2018, 23:51
Bunuel wrote:
How old is Robert now?

(1) The product of his age now and his age five years from now is 24.

(2) Six years from now he will be three times as old as he is now.

Let us assume the age of Robert now as 'x' years.

Statement 1
Age now = x, age after five years = x+5. Given:
x*(x+5) = 24. Only positive value of 'x' that satisfies this is '3'. (3*8 = 24).
This means Robert's age now is '3 years. Sufficient.

Statement 2
Age now = x, age after six years = x+6. Given:
x+6 = 3*x or 2x = 6 or x=3.
This means Robert's age now is '3' years. Sufficient.

Current Student
Joined: 07 Jan 2016
Posts: 1086
Location: India
GMAT 1: 710 Q49 V36
Re: How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

23 Feb 2018, 00:24
Bunuel wrote:
How old is Robert now?

(1) The product of his age now and his age five years from now is 24.

(2) Six years from now he will be three times as old as he is now.

1)

x(x+5) = 24
x^2 + 5x + 24 = 0
x= -8 or 3
age is positive thus age=3

sufficient

2)

x+6 = 3x

x= 3

sufficient

(D) imo
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 4009
Re: How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

23 Feb 2018, 10:10
Top Contributor
Bunuel wrote:
How old is Robert now?

(1) The product of his age now and his age five years from now is 24.

(2) Six years from now he will be three times as old as he is now.

Let N = Robert's age NOW

Target question: What is the value of N?

Statement 1: The product of his age now and his age five years from now is 24.
If N = Robert's age NOW...
then N+5 = Robert's age in 5 years

We can write: N(N + 5) = 24
Expand: N² + 5N = 24
Rewrite as: N² + 5N - 24 = 0
Factor: (N + 8)(N - 3) = 0

So, EITHER N = -8 OR N = 3
Since Robert's age cannot be NEGATIVE, we can conclude with certainty that N = 3
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: Six years from now he will be three times as old as he is now.
If N = Robert's age NOW...
then N+6 = Robert's age in 6 years

We can write: N + 6 = 3N
Solve: N = 3
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Manager
Joined: 26 Sep 2016
Posts: 55
How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

23 Feb 2018, 16:11
St 1) The product of his age now and his age five years from now is 24.
If Robert is today r years old , five years from now he will be r+5 . We can set an equation r(r+5)=24
$$r^2+5r-24=0$$ we can solve for r (we will omit the negative root) sufficient

(2) Six years from now he will be three times as old as he is now. If Robert is today r years old , six years from now he will be r+6. We can set the equation r+6=3r and solve for r sufficient

Non-Human User
Joined: 09 Sep 2013
Posts: 13275
Re: How old is Robert now? (1) The product of his age now and his age  [#permalink]

### Show Tags

29 Jul 2019, 04:57
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: How old is Robert now? (1) The product of his age now and his age   [#permalink] 29 Jul 2019, 04:57
Display posts from previous: Sort by