Three spies—Ex, Why, and Zee— together know 19 different secrets. Ther

Question

Three spies—Ex, Why, and Zee— together know 19 different secrets. There is no overlap of information. How many secrets does Why know?

(1) Ex knows one more than Why and twice as many as Zee.
(2) Why knows three more secrets than Zee.

paidlukkha · Answer

S1 1 
x=y+1
x=2z
we know together there are 19
i.e. x-y-z = 
4,7,8

S2 
all we know is 
y = z + 3
but we need to know x's part
Not suff

Ans A

GMATWhizTeam · Answer

Solution 
 Step 1: Analyse Question Stem 
 • Ex, Why, and Zee know 19 different secrets.
 o Let us assume that Ex, Why and Zee know x, y and z secrets, respectively. 
• There is no overlap of secrets.
 o This means,  x + y + z = 19 ………Eq. (i)   
We need to find the value of y.
 Step 2: Analyse Statements Independently (And eliminate options) – AD/BCE 
 Statement 1:  Ex knows one more than Why and twice as many as Zee.
 • According to this statement :  x = y+1  and
 o   x =2z⟹ z =\frac{x}{2} = \frac{(y + 1)}{2}  
• Substituting the above values of x and z in Eq(i), we get,
 o  (y+1) + y +\frac{(y+1)}{2 }= 19   
We can easily solve the above equation and find the value of y.
Hence, statement 1 is sufficient and we can eliminate answer Options B, C and E.

Statement 2:  Why knows three more secrets than Zee.
 • According to this statement;  y = z+3 
• This statement neither gives any information about x nor it gives the exact value of z. Thus, we cannot determine the value of y from this statement alone. 
Hence, statement 2 is NOT sufficient.
Thus, the correct answer is  Option A.

sauravleo123 · Answer

x+y+z=19
y=?
Statement 1:x=y+1
Also x=2z
So y+1+y+(y+1/2)=19
Can be solved for the value of y
Sufficient
Statement 2: y=z+3
There is no way to calculate y without the value of z. But in gmat its better to check
x+2y=22
2y=22-x
y=11-x/2
If x=2, y=10 and z=7
If x=4, y=9 and z=6
Two different values
Insufficient
A

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