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Rita earns scores of 83, 87, 85, 88, and 90 on her five chapter tests for a certain class and a grade of 82 on the class project.
The overall average for the course is computed as follows: the average of the five chapter tests makes up 30% of the course
grade; the project accounts for 30% of the grade; and the final exam accounts for 40%. What scores can Rita earn on the final
exam to earn a "B" in the course if the cut-off for a "B" is an overall score greater than or equal to 80, but less than 90? Assume>that 100 is the highest score that can be earned on the final exam and that only whole-number scores are given.>To obtain a "B", Rita needs to score between>and>inclusive


Sagot :

Given:

Rita earns scores of 83, 87, 85, 88, and 90 on her five-chapter tests for a certain class.

And a grade of 82 on the class project.

First, we will find the average of the scores of the five tests

[tex]5-tests\text{ }average=\frac{83+87+85+88+90}{5}=\frac{433}{5}=86.6[/tex]

The overall average for the course is computed as follows:

30% of the course grade ⇒ Rita get 86.6

30% of project grade ⇒ Rita get 82

40% of the final exam ⇒ let Rita get x

We will find the value of x provided that Rita will earn a "B" score

a "B" is an overall score greater than or equal to 80, but less than 90

So, we will find (x) as follows:

[tex]\frac{30*86.6+30*82+40*x}{100}\ge80[/tex]

Solve the inequality to find (x):

[tex]\begin{gathered} 5058+40x\ge8000 \\ 40x\ge8000-5058 \\ 40x\ge2942 \\ x\ge\frac{2942}{40} \\ \\ x\ge73.55 \end{gathered}[/tex]

And the upper limit will be as follows:

[tex]\frac{30\times86.6+30\times82+40x}{100}<90[/tex]

Solve to find (x):

[tex]\begin{gathered} 5058+40x<9000 \\ 40x<9000-5058 \\ 40x<3942 \\ x<\frac{3942}{40} \\ \\ x<98.55 \end{gathered}[/tex]

So, the answer will be:

To obtain a "B", Rita needs to score between 73.55 and 98.55