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