|
|
Averages - January 28, 2005
The question for the day is a math question from the topic of Averages in Arithmetic.
Question
The arithmetic mean of the 5 consecutive integers starting with 's' is 'a'. What is the arithmetic mean of 9 consecutive integers that start with s + 2?
A. 2 + s + a
B. 2 + a
C. 2s
D. 2a + 2
E. 4 + a
The correct choice is (E) and the correct answer is 4 + a.
Explanatory Answer
The fastest way to solve such questions is to assume a value for 's'.
Let s be 1.
Therefore, the 5 consecutive integers that start with 1 are 1, 2, 3, 4 and 5.
The average of these 5 numbers is 3.
9 consecutive integers that start with 1 + 2 are 3, 4, 5, 6, 7, 8, 9, 10 and 11
The average of these 9 number is 7.
Now, let us take a look at the answer choices and substitute '1' for 's' and '3' for 'a'.
The only choice that provides us with an answer of '7' is choice (E).
|
|
|
