Question:

Mean and variance of 8 numbers $x,y,10,12,6,12,4,8$ are 9 and 9.25. If $x>y$, then $3x-2y$ is equal to _______

Step-by-Step Solution

Key Concept: $x+y=20$ from mean. $x^2+y^2=218$ from variance. Solve system.

$x=13,y=7$. $3x-2y=25$.

Correct Answer: 25