Amount charged for downloading individual songs = x dollars Amount charged for downloading an entire song album = y dollars Person A: 6x + 2y = 25.92 3x + y = 12.96 y = 12.96 - 3x Person B: 4x + 3y = 33.93 Putting the value of y from the first equation in the second we get x = 0.99 dollars Putting the value of x in the first equation we get y = 12.96 - 3x = 12.96 - 2.97 = 9.99 dollars
Let x be a random variable representing the length of a text messaging conversation, then P(x > 3) = 1 - P(x < 3) = 1 - P(z < (3 - 2)/0.5) = 1 - P(z < 2) = 1 - 0.97725 = 0.02275
