Bunuel wrote:

If the average (arithmetic mean) of 6 numbers is 30, what is the average of all the numbers that are less than 30?

(1) Two of the numbers are 30 or greater.

(2) The average of the numbers that are greater than or equal to 30 is 48.

To calculate the average we need the sum and the number of items.

We'll look for statements that give the required information, a Logical approach.

(1) To calculate the average of the two numbers we need their sum!

Insufficient.

(2) This time we're given their average but not the amount of numbers!

Insufficient.

Combined:

Now we know how many numbers are greater or equal to 30 and their average so can calculate their sum.

That means we know the sum of the rest of the numbers and can calculate their average.

Sufficient!

(C) is our answer.

_________________

David

Senior tutor at examPAL

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