If the average (arithmetic mean) of a, b, and c is 10, what is the ave

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If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

(1) The average of c, d, e, and f is 10.
(2) The standard deviation of c, d, e, and f is 0.

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yashikaaggarwal · Answer

Given: Average of ABC = 10
(A+B+C)/3 = 10
A+B+C = 30

To find: (A+B+C+D+E+F)/6 = ?

Statement 1: (C+D+E+F)/4 = 10
C+D+E+F = 40
Missing values of A and B
(Insufficient)

Statement 2: Standard Deviation of C,D,E and F is zero 
That means values of C=D=E=F
But what is the value?
(Insufficient)

Combining both: C+D+E+F = 40
4C = 40
C = 10 {=D=E=F}
(A+B+C = 30
A+B = 30-10 = 20)

Average of A+B+C+D+E+F =
20+40/6 = 60/6 = 10
(Sufficient)

Answer is C

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Varunsawhney8 · Answer

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

(1) The average of c, d, e, and f is 10.
(2) The standard deviation of c, d, e, and f is 0.

Given 
(a+b+c)/3=10
hence
a+b+c=30

We need to calculate
(a+b+c+d+e+f)/6

We just need to calculate
d+e+f as we have value of sum for the other half

Statement-1
(1) The average of c, d, e, and f is 10.
 implies 
c+d+e+f=40

We will get nothing from here

Insufficient

(2) The standard deviation of c, d, e, and f is 0.
It implies all values are similar
but we will not get any distinct particular value from here

Insufficient

Combining 1 and 2

We get

C=d=e=f=10

Hence we will get our average from the above
Both statement together are sufficient

Dan1sh · Answer

If SD of c, d, e, f is 0.
It can be inferred that mean of these numbers is equal to each individual number. So, c, d, e, f have same numerical value.

Since we don't know that value we cannot calculate mean of a, b, c, d e, f. Hence statement 2 alone is not sufficient

But, with statement 1+ Statement 2, mean can be calculated.

IMO:C

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Loser94 · Answer

Option C 
Both statement are required.

State1 : Average of c d e f is 10. Total sum will be 40 for CDEF
But ABC has average of 10. that means sum of ABC=30 & CDEF= 40 C is common in both can have any value.
so option A & D are incorrect.

STate 2: Standard deviation between c d e f is 0 means
all are same numbers. Still we can't get the answer.
Option B is incorrect.

Using both options we Get value of C=D=E=F=10 and we know sumof ABC is 30. so we get the answer.

exc4libur · Answer

(1) insufic
abc=30, cdef=40
c=?

(2) insufic
c=d=e=f

(1/2) sufic
abc=30 + 4c=40, c=10
ab=20, cdef=40

ans (C)

MayankSingh · Answer

IMO C

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

a+b+c=10x3=30
to find average: (d+e+f) required.

(1) The average of c, d, e, and f is 10.

From here, we know (c+d+e+f)= 40
But we don't know the value of c to find (d+e+f) 
  Insufficient

(2) The standard deviation of c, d, e, and f is 0.
 
 Standard deviation is zero when numbers are equal.
So, c= d= e= f 
But values of d, e, f Or, d+e+f  
  Insufficient

Together 1 & 2,    
 c= d= e= f= 2.5
So, d+e+f=7.5 
  Sufficient

HoneyLemon · Answer

imo  C  .

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?
a+b+c = 30 . 
(a+b+c+d+e+f)/6 = ? 
=> (30+d+e+f)/6 = ?

(1) The average of c, d, e, and f is 10.
c+d+e+f = 40
a+b+c = 30
70 -c =a+b+c+d+e+f . 
No info about c . SO  not sufficient  . 
(2) The standard deviation of c, d, e, and f is 0.
 again 
c, d, e, and f = 0 or equal . 
 SO not sufficient .

combining . 
c, d, e, and f cannot be 0. 
so c, d, e, and f = 10 . 
 so   sufficient

NiftyNiffler · Answer

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

(1) The average of c, d, e, and f is 10.
(2) The standard deviation of c, d, e, and f is 0.

We are given that a + b+ c = 30 and we are asked what is the value of a+b+c+d+e+f ? (paraphrasing the question)

st1) c+d+e+f = 40 , INSUFFICIENT since c is common between what's given and st1 and can take any value

st2) SD of c, d, e and f is 0, which means all variables are equal. INSUFFICIENT since we don't know values of these variables

st1 and st2 taken together, c = d = e = f = 2.5 , so Avg of a+b+c+d+e+f = 37.5/5 = 7.5 SUFFICIENT

So, the answer should be  C

kush09 · Answer

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

solution:
A.M of a,b,c is 10
=> a+b+c= 30
we need to find A.M. of a, b, c, d, e, and f

(1) The average of c, d, e, and f is 10.
 -- Considering statement 1 alone:
Sum of c, d, e, f = 40
But, as we don't know the value of C independently, we cannot find unique value for A.M. of the set. 
 statement 1 alone is not sufficient.

(2) The standard deviation of c, d, e, and f is 0. 
 -- Considering statement 2 alone:
From this statement we know c=d=e=f, but we don't know their absolute value, it could be 5,10,20.  
 statement 2 alone is not sufficient.

Combining both the statement:
 From 1: As A.M of c, d, e, and f is 10
From 2: S.D of c, d, e, and f is 0, therefore each term is 10

=> c+d+e+f = 40 or d+e+f = 30
=> a+b+c+d+e+f = 60
=> A.M of set is 10
 
 Answer C

AdiBir · Answer

Given:  
Mean of  a, b, c  is 10.
So  a + b + c = 30 .

To Find:  
Mean of a, b, c, d, e, f.
or we need find  d + e + f .

Now coming to the statements:

1)  says mean of  c, d, e, f  is 10. 
So  c + d + e + f = 40 . But we need value of only  d + e + f . 
  Not Sufficient  .

2)  says standard deviation of  c, d, e, f (assuming from mean) is  0 .
So this means that all four are equal to mean. But we don't know the mean.
  Not Sufficient  .

Combining 1) and 2) .
We know  c, d, e, f  are equal to their mean and we know the mean is  10 .
So we know  d + e + f .
Hence combined  1)  and  2)  are   Sufficient  .

Answer is  C .

minustark · Answer

If the average (arithmetic mean) of a, b, and c is 10, what is the average of a, b, c, d, e, and f?

(1) The average of c, d, e, and f is 10.
(2) The standard deviation of c, d, e, and f is 0.

1) If the value of c is 20, then the sum of a,b,c,d,e and f will be 50 (a+b+c = 30, so a+ b = 10, and c+d+e+f = 40, so d + e+ f = 20) and the average will be 8.333. Again if all of them are equal to 10 then the average will be 10. Not sufficient.

2) That means c, d, e and f are all equal, but without the information about c we cannot get the average. not sufficient.

Together, as c ,d,e,f all are 10 and a+b = 20. so the average will always be 10. sufficient.

C is the answer.

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If the average (arithmetic mean) of a, b, and c is 10, what is the ave

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If the average (arithmetic mean) of a, b, and c is 10, what is the ave

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