Question

a student must have the average (the mean) on five tests that is greater than or equal to 80% but less than 90% to receive a final grade of B. Devons grades on the first four tests were 70%, 65%, 90% and 77%. What range of grades on the fifth test would give him a B in the course? (Assume that 100% is the highest grade possible). Enter the range of grades necessary for Devon to earn a B average. _____% less than or greater to x less than or greater to 100%.

Answer 1

Shouldn't it be 98%?

Answer 2

oh yeah.. sorry..

Answer 3

\[\Large \begin{array}{l}
\frac{{70 + 65 + 90 + 77 + x}}{5} \ge 80\\
\frac{{302}}{5} + \frac{x}{5} \ge 80\\
302 + x \ge 400\\
x \ge 98
\end{array}\]

Answer 4

\[80\leq \frac{65+70+77+90+x}{5}<90\] is your equation

Answer 5

probably my brain is not working correctly

Answer 6

Heh mine's never working correctly, especially when tired.

Answer 7

actually it is not an equation it is an inequality.
more coffee!

Answer 8

To the coffee pot!

Answer 9

so is the answer 98%

Answer 10

I need to enter the range of grades

Answer 11

\[80\leq \frac{302+x}{5}<90\]
\[400\leq 302+x<450\]
\[98\leq x<142\]
guy doesn't have a chance and should try for a C+

Answer 12

\[x\geq 98\]

Answer 13

btw i hope this is a typo

less than or greater to x less than or greater to 100%.

there is no such thing is "less than or greater to"

Answer 14

i meant equals sorry

Answer 15

98% is not the correct answer

Answer 16

It has to be. His final score must be equal to or greater than 98% to get an average of 80% or more.