In a certain class, \(x\) students are \(10\) years old, and the remaining \(y\) students are \(11\) years old. What is

[Vincen]

In a certain class, \(x\) students are \(10\) years old, and the remaining \(y\) students are \(11\) years old. What is the average (arithmetic mean) age of all students in the class?

A. \(\dfrac{x+y}{21}\)

B. \(\dfrac{10x+11y}{21}\)

C. \(\dfrac{110xy}{x+y}\)

D. \(\dfrac{110xy}{xy}\)

E. \(\dfrac{10x+11y}{x+y}\)

Answer: E

Source: Magoosh

[Scott@TargetTestPrep]

In a certain class, \(x\) students are \(10\) years old, and the remaining \(y\) students are \(11\) years old. What is the average (arithmetic mean) age of all students in the class?

A. \(\dfrac{x+y}{21}\)

B. \(\dfrac{10x+11y}{21}\)

C. \(\dfrac{110xy}{x+y}\)

D. \(\dfrac{110xy}{xy}\)

E. \(\dfrac{10x+11y}{x+y}\)

Answer: E

Solution:

The sum of the ages of x students is 10x years old, and the sum of the ages of y students is 11y years old. Since there is a total of x + y students, the average age is (10x + 11y) / (x + y) years old.

Answer: E