Q1. You have a box of 8 coins. 7 of them are normal fair coins, while 1 has tails on both sides. You pick a coin at random from the box and toss it 3 times, and get 3 tails. The probability that the coin you chose was one with tails on both sides can be expressed in the form M /N, where M and V are relatively prime positive integers (i.e. their greatest common divisor is 1). Compute M + N.