12 Days of Christmas GMAT Competition - Day 4: Currently, on a certain

Question

12 Days of Christmas 2024 - 2025 Competition with $40,000 of Prizes

Currently, on a certain website, out of all online users, 2,400 are registered users, and 1,000 are male. How many users are currently online?

(1) The number of online female users is twice the number of online unregistered users.

(2) Among the online users, 800 are registered males.

Bunuel · Accepted Answer

GMAT Club's Official Explanation:

Currently, on a certain website, out of all online users, 2,400 are registered users, and 1,000 are male. How many users are currently online?

Let T represent the total number of online users. The breakdown is as follows:

Registered  
 Un-registered  
 TOTAL  
 
  Male

1,000 
 
  Female

T - 1,000  
 
  TOTAL  
 2,400 
 T - 2,400 
 T

(1) The number of online female users is twice the number of online unregistered users.

This implies that T - 1,000 = 2(T - 2,400), which gives T = 3,800. Sufficient.

(2) Among the online users, 800 are registered males.

This gives the following breakdown:

Registered  
 Un-registered  
 TOTAL  
 
  Male 
 800 
  200  
 1,000 
 
  Female  
  1,600  
  
 T - 1,000  
 
  TOTAL  
 2,400 
 T - 2,400 
 T

From this, we still do not have enough information to determine the total number of online users, T. Not sufficient.

Answer: A.

hr1212 · Answer

Number of male users: 1000
Number of registered users: 2400

Let R be registered user, UR be unregistered user, M be male users and F be female users.

Statement 1:

R 
 UR 
 T 
 
  M

1000 
 
  F

2x 
 
  T 
 2400 
 x 
 y

2400 + x = 1000 + 2x
x = 1400
y = 2400 + x = 3800

This statement is sufficient.

Statement 2:

R 
 UR 
 T 
 
  M 
 800 
 200 
 1000 
 
  F 
 1600

T 
 2400 
  
 y

Cannot calculate the value of y here, so this statement is insufficient.

Answer: A

HarshaBujji · Answer

Given : 
 U: Total number of online users (what we want to find).
 R: Number of registered users =2400
 M: Number of online male users =1000
 F: Number of online female users.
 Un: Number of online unregistered users.

So U = Un+2400. and U=1000+F.

(1) The number of online female users is twice the number of online unregistered users.

From this f = 2Un, So using both the above equations

U - 1000 = 2(U-2400) => U=3800.
 
Hence Stmt 1 is sufficient

(2) Among the online users, 800 are registered males.
 
We cannot get the U using this info as 3 variables, 2 equations are given.

Hence Stmt 2 is not sufficient.  
 
IMO A

Kinshook · Answer

Currently, on a certain website, out of all online users, 2,400 are registered users, and 1,000 are male. How many users are currently online?

Online users 
 Male 
 Female 
 Total 
 
  Registered

2400 
 
  Unregistered

Total 
 1000 
  
 x=?

(1) The number of online female users is twice the number of online unregistered users.

Online users 
 Male 
 Female 
 Total 
 
  Registered

2400 
 
  Unregistered

y 
 
  Total 
 1000 
 2y 
 x=2400+y=1000+2y

x = 2400+y = 1000+2y
y = 1400
x = 2400+1400 = 3800
3800 users are currently online
SUFFICIENT

(2) Among the online users, 800 are registered males.

Online users 
 Male 
 Female 
 Total 
 
  Registered 
 800 
 2400-800=1600 
 2400 
 
  Unregistered 
 1000-800=200 
 y 
 200+y 
 
  Total 
 1000 
 1600+y 
 x=2600+y

Since the value of y is unknown
NOT SUFFICIENT

IMO A

Krunaal · Answer

Let, T: Total online users
R: No. of online registered users => 2400
U: No. of online unregistered users => T - 2400
M: No. of male online users => 1000
F: No. of female online users => T - 1000

We need to find T

Statement 1

F = 2U
T - 1000 = 2(T - 2400)
 T = 3800   SUFFICIENT

Statement 2

If RM = 800, then UM = 200, we have RF = 1600, but  we don't know UF  to calculate total online users.  NOT SUFFICIENT

Answer A.

aanamahmed12 · Answer

Answer A.

Solving by the matrix method. We need to find X
    
 Male 
 Female

Registered

2400 
 
  Unregistered

1000 
  
 X

Statement 1.
Taking online unregistered users as Y
Online female users 2Y

Male 
 Female

Registered

2400 
 
  Unregistered

Y

1000 
 2Y 
 X

We get 2 equations

2400 + Y = X
1000 + 2Y = X

We can solve this to get X and Y
Sufficient

Statement 2.

Male 
 Female

Registered 
 800 
 1600 (Deriving from 2400-800) 
 2400 
 
  Unregistered 
 200 (deriving from 1000-800)

1000 
  
 X

I still don't know what X is
Insufficient.

missionmba2025 · Answer

Registered 
 Not Registered

Male

1000 
 
  Female

x - 1000

2400 
 x - 2400 
 x

1) The number of online female users is twice the number of online unregistered users.

x - 1000 = 2 (x - 2400)

We have only one unknown variable. Hence, this statement is sufficient to find x.

2) Among the online users, 800 are registered males.

We have no information on the number of females. Hence, the statement is not sufficient.

Registered 
 Not Registered

Male 
 800 
  
 1000 
 
  Female

x - 1000

2400 
 x - 2400 
 x

Option A

Prakhar9802 · Answer

Table method is perfect for these kind of questions -
Let the total online users be x.

Registered 
 Unregistered

Males

1000 
 
  Females

x-1000

2400 
 x-2400 
 x

Statement 1 -

F = 2*(unregistered)

x-1000 = 2*(x-2400)

We have one variable, one equation, we can get the answer easily. SUFFICIENT

Statement 2 -

Registered males = 800
    
 Registered 
 Unregistered

Males 
 800 
 200 
 1000 
 
  Females 
 1600 
 y 
 x-1000

2400 
 x-2400 
 x

If we let unregistered females be Y

Y = x-1000-1600
y= x-2600

Y = x-2400-200
y=x-2600

We can see that we have 2 variables and 1 equation, we cannot solve.

Therefore, INSUFFICIENT.

FINAL ANSWER - Option A

Karanjotsingh · Answer

What we know from the question: 
 
 2,400 registered users 
 1,000 total males 
 Need to find total online users  
 
  From Statement (1): 
 
 Female users = 2 × unregistered users Let's say unregistered = x 
 Then females = 2x 
 Total users = registered + unregistered = 2,400 + x 
 Also, total users = males + females = 1,000 + 2x 
 Therefore: 2,400 + x = 1,000 + 2x 
 Solving: 2,400 - 1,000 = 2x - x 
 1,400 = x So total users = 2,400 + 1,400 = 3,800  
 
  From Statement (2): 
 
 800 registered males This alone doesn't give us enough information to find the total users  
  
Therefore, Statement (1) ALONE is sufficient. We get a unique answer: 3,800 users. Statement (2) alone doesn't help us find the total.

The answer is A.

Navya442001 · Answer

Given: For all online users,

Registered 
 Unregistered 
 Total 
 
  Male

1000 
 
  Female

Total 
 2400 
  
 x

We need to find x here

Statement 1 
 The number of online female users is twice the number of online unregistered users. 
Let the number of total unregistered users be y, the total female users will be 2y

Registered 
 Unregistered 
 Total 
 
  Male

1000 
 
  Female

2y 
 
  Total 
 2400 
 y 
 x

therefore x= 2400 + y
and x= 1000 + 2y

Equating both 
2400 + y = 1000 +2y
y = 1400
therefore x = 3800.  Hence, Statement 1 is sufficient.

Statement 2 
 Among the online users, 800 are registered males.

Registered 
 Unregistered 
 Total 
 
  Male 
 800 
 200 
 1000 
 
  Female 
 1600

Total 
 2400 
  
 x

However, we don't have sufficient information to find the value of x.  Hence, Statement 2 is not sufficient.

Lizaza · Answer

This task is easily solved with a table, where we're looking for the total number of online users T against two cross-categories: gender and registration    (attached).

(1) In this case, we can insert 2x and x as shown in the table - and then:  
  T=2400+x=1000+2x  
  x=2400-1000=1400  
  T=2400+1400=3800  
  Sufficient.

(2) From registered males, we can get registered females (1600) and unregistered males (200). However, the number of unregistered females is impossible to find.  Insufficient.

Therefore,    the answer is A.

LunaticBabe · Answer

First create a table with the given values. 
     
 male 
 female 
 total 
 
  registered

2400 
 
  unregistered

total 
 1000

Using this info and the first statement. take total unregistered users = x and total female becomes 2x. 
Now, 1000+2x = 2400 + x. solving this we can find total current online users. 
 Using the second statement, I was unable to create an equation which can give me the current online users.

Hence, I choose answer as A.

12 Days of Christmas GMAT Competition - Day 4: Currently, on a certain

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	Registered	Un-registered	TOTAL
Male			1,000
Female			T - 1,000
TOTAL	2,400	T - 2,400	T

Online users	Male	Female	Total
Registered			2400
Unregistered
Total	1000		x=?

GMAT Data Sufficiency (DS) Questions

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