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 an SSB signal when the modulating signal is x(t). Let x(t) represents the complex conjugate of x(t) and is its Hilbert transform. The envelope of SSB signal is:

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)?