Final answer:
The population variance of y when y=2x is 40.
Step-by-step explanation:
To find the population variance of y when y = 2x, we need to understand how the variance changes when a random variable is multiplied by a constant. When a random variable is multiplied by a constant, the variance of the new random variable is the square of the constant multiplied by the variance of the original random variable.
In this case, y = 2x, so the population variance of y is (2^2) * (population variance of x). Since the population variance of x is given as 10, the population variance of y is (2^2) * 10 = 40.