not use excel

Before going hunting, a person practices shooting an arrow at a target. Distance (d) between the center point of the target and the point obtained in the release of the arrow distributed as an exponential with mean 10. If the person gets the maximum score when the distance d is less than 8. a) Find the probability that in 50 tosses he gets the maximum score at least once. b) Find the probability that 10 tosses are needed to get three scores. maxims