test31 #11

dunkin77 · Posted: Mon Apr 23, 2007 11:11 am Post subject: test31 #11

11. Which of the following procedures is always equivalent to adding 5 given numbers and then dividing the sum by 5 ?
I. Multiplying the 5 numbers and then finding the 5th root of the product.
II. Adding the 5 numbers, doubling the sum, and then moving the decimal point one place to the left.
III. Ordering the 5 numbers numerically and then selecting the middle number.
(A) None
(B) I only
(C) II only
(D) III only
(E) I and III

Hi,
I though the answer is D) but actually C) is the answer -- can anyone help?

rajeshvellanki · Posted: Mon Apr 23, 2007 1:56 pm Post subject:

pretty simple man... 1/5=0.2

option 3 is median and what they gave is mean.. so mean <> median.

2(a+b+c+d+e) and moving decimal place by 1 is nothing but 1/5=0.2

Hope you got it.

So answer is C.

R

Cybermusings · Posted: Wed Apr 25, 2007 6:02 am Post subject:

It's simple man...

When u pick 5 numbers say x,y,z,u,v
Sum = (x+y+z+u+w)
Sum / 5 = Mean

Now if you double the mean i.e 2S, the result will stay unchanged if you multiply the denominator or the number 5 with 2
So 2S/5*2 = S/5

Hence II is correct

III for sure is wrong

The only answer which fits here is C