A fully charged mobile phone with a 12 V battery is good for a 20 minute talktime. Assume that, during the talk time, the battery delivers a constant current of 2 A and its voltage drops linearly from 12 V to 10 V as shown in the figure. How much energy does the battery deliver during this talk time?
Consider two independent random variables x and y with identical distributions. The variables X and Y take 0, 1 and2 with probabilities and respectively. What is the conditional probability P(X + Y = 2| X - Y = 0)?