statistic worksheet

1. A dart player throws 10 darts at the dart board. He has a 20% chance of hitting the bull’s eye each time. If throws are independent, what is the probability that he hits the bull’s eye exactly twice?

2. A basketball coach has 20 players on his team. 7 of them are upperclassmen and the rest are lowerclassmen. He randomly selects 5 players to start a game.

a. Explain why we can’t use the binomial distribution to find the probability that 3 of the starters are upperclassmen.

b. Find the probability that 3 of the 5 starters are upperclassmen.

3. A child counts the number of cracks in the sidewalk along the block she lives in (about 1/8 mile of sidewalk). Suppose the expected number of cracks in a block of sidewalk is 2.

a. Which distribution would be best to use to model this situation? Explain.

b. What is the probability that she observes 3 or more cracks?

c. What is the probability that she observed exactly 2 cracks in ½ of the block?