Question

Donovan wants to earn a 70% in Mr. Mottola's class. He knowshe currently has an 66% in the class after 8 grades. What is theminimum grade Donovan would need to earn in order to have a70%.Help ?

Answer 1

For this case we need to remember the definition of average given by:

$\text{Mean}=\frac{\sum ^n_{i=1}x_i}{n}$

We know that the passing score for the two semestrers is 70%. We also know that the score for Semester 1 is 55

And for semester 2 we have that RC3= 64 and RC4= 78. The average of both RC is:

$Rc=\frac{64+78}{2}=71$

This average represent the 90% of the grade for the second semester. We also know that the final spring exam (SF) is 10% of the second semester grade.

In order to pass we need to satisfy the following:

$\frac{55+\left\lbrack 0.9\cdot(71)+0.1\cdot SF\rbrack\right\rbrack }{2}=70$

And for this case we want to solve for SF the spring final score required in order to pass. Solving we got:

$SF=\frac{(70\cdot2)-55-63.9}{0.1}=211$

He needs 211 in the final spring exam in order to get an 85 for the second semester and reach the 70% to pass