Jane has found that the grade she earns on a test is determined bu the number of
ID: 3039016 • Letter: J
Question
Jane has found that the grade she earns on a test is determined bu the number of hours spent studying for that test. This relationship is giving by the function y=0.55x + 76.8, where y is the grade earned on the test and x is the number of hours spent studying for the test. Solve the linear double inequality, 80<= 0.55x + 76.8 <= 89, using algebraic methods to determine how many hours Jane should study to earn a test grade between 80 and 89. Use interval notation when stating the solution.
The <= is less than equal to
Explanation / Answer
80 <= 0.55x + 76.8 <= 89
subtract 76.8 from each side
80 - 76.8 <= 0.55x <= 89 - 76.8
3.2 <= 0.55x <= 12.2
divide by 0.55
3.2/0.55 <= x <= 12.2/0.55
5.82 <= x <= 22.18
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