Apair of dice is rolled. what is the conditional probability that the sum of numbersthat came up on the top of the dice is nine given the information that
(a) at least one of the two dice came up six?
(b) both dice came up odd?
(c) one die came up odd and the other even?

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).