In a game, a player throws a ball at a target. If they hit the
target, then 7 points are added to their score. If they miss the target,
then points are subtracted from their score. A player’s score begins at 0, and it is possible for a player to have a negative score.
What is Shane’s score after throws if of the throws are hits and 2 of the throws are misses?
After exactly hits and 6 misses, Susan’s score is 59. What is the value of ?
After exactly throws, Souresh’s score is greater than 85 and less than 105. If exactly of these throws are misses, determine all possible values of the positive integer .
, 2022
Solution
Each hit adds 7 points to Shane’s score, and so 4 hits adds points to his score. For each miss, 3 points are subtracted from Shane’s score, and so 2 misses subtracts points from his score. A player’s score begins at 0, and so after these 6 throws, Shane’s score is . Solution 1 After exactly hits and 6 misses, Susan’s score is given by the expression or . After these throws, Susan’s score is 59, and so . Solving this equation, we get or , and so . Solution 2 Susan’s 6 misses decrease her score by points. Since her score is 59, then Susan must have scored points from hits. Since each hit is worth 7 points, then the value of is . Solution 1 We begin by making an initial guess at the value of , and then systematically adjust the value upward or downward as needed. If we begin with for example, then the number of hits is and Souresh’s score is . Since this score is greater than 105, then the value of is greater than 3 (more misses means fewer hits and a lower score). When , the number of hits is and Souresh’s score is . Since this score is greater than 85 and less than 105, then 4 is a possible value of . When , the number of hits is and Souresh’s score is . This score is also greater than 85 and less than 105, and so 5 is a possible value of . When , the number of hits is 14 and Souresh’s score is . This score is less than 85 and so 6 is not a possible value of . Continuing to increase the number of misses will further decrease Souresh’s score, and thus the only possible values are and . Solution 2 Since Souresh makes 20 throws and of these throws are misses, then the remaining throws are hits. After exactly hits and misses, Souresh’s score is given by the expression or . Since Souresh’s score () is greater than 85, then must be less than 55 (note that $140 - 85 =
55m <
Since and is a positive integer, then . Since Souresh’s score is less than 105, then must be greater than 35 (note that ) and so . Since and is a positive integer, then . Thus, is a positive integer and , and so or . (We can check that when , Souresh’s score is , and when , Souresh’s score is .)


