Each hit adds 7 points to Shane’s score, and so 4 hits adds 7×4=28 points to his score.
For each miss, 3 points are subtracted from Shane’s score, and so 2
misses subtracts 3×2=6 points
from his score.
A player’s score begins at 0, and so after these 6 throws, Shane’s score
is 28−6=22.
Solution 1
After exactly h hits and 6
misses, Susan’s score is given by the expression 7×h−3×6 or 7h−18.
After these throws, Susan’s score is 59, and so 7h−18=59.
Solving this equation, we get 7h=59+18 or 7h=77, and so h=11.
Solution 2
Susan’s 6 misses decrease her score by 3×6=18 points.
Since her score is 59, then Susan must have scored 59+18=77 points from hits.
Since each hit is worth 7 points, then the value of h is 77÷7=11.
Solution 1
We begin by making an initial guess at the value of m, and then systematically adjust the
value upward or downward as needed.
If we begin with m=3 for example,
then the number of hits is 20−3=17
and Souresh’s score is 7×17−3×3=119−9=110.
Since this score is greater than 105, then the value of m is greater than 3 (more misses means
fewer hits and a lower score).
When m=4, the number of hits is
20−4=16 and Souresh’s score is
7×16−3×4=112−12=100.
Since this score is greater than 85 and less than 105, then 4 is a
possible value of m.
When m=5, the number of hits is
20−5=15 and Souresh’s score is
7×15−3×5=105−15=90.
This score is also greater than 85 and less than 105, and so 5 is a
possible value of m.
When m=6, the number of hits is 14
and Souresh’s score is 7×14−3×6=98−18=80.
This score is less than 85 and so 6 is not a possible value of m.
Continuing to increase the number of misses will further decrease
Souresh’s score, and thus the only possible values are m=4 and m=5.
Solution 2
Since Souresh makes 20 throws and m of these throws are misses, then the
remaining 20−m throws are
hits.
After exactly 20−m hits and m misses, Souresh’s score is given by the
expression 7(20−m)−3m or 140−10m.
Since Souresh’s score (140−10m) is
greater than 85, then 10m must be
less than 55 (note that $140 - 85 =
55)andsom <
1055$.
Since 1055=521 and
m is a positive integer, then m≤5.
Since Souresh’s score is less than 105, then 10m must be greater than 35 (note that
140−105=35) and so m>1035.
Since 1035=321 and
m is a positive integer, then m≥4.
Thus, m is a positive integer and
4≤m≤5, and so m=4 or m=5.
(We can check that when m=4,
Souresh’s score is 7×16−3×4=112−12=100, and when
m=5, Souresh’s score is 7×15−3×5=105−15=90.)