The following table shows the probability of rolling the numbers 1 through 8 on a fair 8-sided die.
х
1
1 2 3 4 5 6 7
8
P(X) 1/8 1/8 1/8 1/8 1/8 1/8 1/8 1/8
What is the standard deviation of the random variable X, "the number that
comes up on the die"?
A. 1.708
B. 3.745
O C. 14.028
D. 2.291
O E. 3.5

Amass weighing 16 pounds stretches a spring 8/3 feet. the mass is initially released from rest from a point 2 feet below the equilibrium position, and the subsequent motion takes place in a medium that offers a damping force that is numerically equal to 1/2 the instantaneous velocity. find the equation of motion if the mass is driven by an external force equal to f(t)=cos(2t).