If P*Q means (P + Q)/2, what is the value of 3*(6*8)?

What is the standard deviation of the following data set rounded to the nearest tenth? 3, 17, 18, 15, 12, 21, 9

Me, prove a quadrilateral with vertices g(1,-1), h(5,1), i(4,3) and j(0,1) is a rectangle using the parallelogram method and a rectangle method.

Which exponential function has an initial value of 2? f(x) = 2(3x) f(x) = 3(2x)