Multiple choice

The average age of a class of 6 girls is x years. Four new girls of ages x - 2, x + 2, x + 4 and x + 6 join the class. What is the new average age (in years) of the class?

  1. x + 1

  2. x + 2

  3. 2.5x

  4. x + 2.5

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Initial sum = 6x. New sum = 6x + (x-2) + (x+2) + (x+4) + (x+6) = 6x + 4x + 10 = 10x + 10. Total girls = 6 + 4 = 10. New average = (10x + 10) / 10 = x + 1.

AI explanation

The total age of the original 6 girls is 6 multiplied by x, giving 6x. The sum of the ages of the four new girls is x minus 2 plus x plus 2 plus x plus 4 plus x plus 6, which simplifies to 4x plus 10. The new total age for all 10 girls is 6x plus 4x plus 10, giving 10x plus 10. Dividing this total by 10 gives a new average of x plus 1.