## Probability

From the Washington State 1996 Math Olympiad

 1). (2 points) Of all the families that have only two children, what is the probability that at least one is a girl? Answer:__________ TEAM NO ____ TEAM MEMBERS: ___________________ ___________________ ___________________ ___________________
 2). (3 points) A bag contains red, white and blue marbles. The probability of drawing a red marble is 1/3 and the probability of drawing a white marble is 1/5. What is the probability of drawing a blue marble? Answer:__________ 3). (3 points) A bag contains 2 yellow marbles, 4 blue marbles and 6 red marbles. How many blue marbles must be added to the bag to make the probability of drawing a blue marble 1/2 or 50%? Answer:__________ 4). (3 points) In a game you flip 3 chips. Chip #1's sides are blue and red; #2's are blue and white; and #3 has red and white. The first player gets a point if any 2 chips match. To be fair, how many points should the second player get if all 3 chips are different? Answer:__________ 5). (3 points) A bag has 10 candies. We drew a candy out, looked at it, and put it back 10 times, and we noticed we got 4 fireballs. We repeated the experiment four times and got 2, 5, 4, and 2 fireballs. How many fireballs are most likely to be in the bag? Answer:__________