After 6 exams, Carl has a mean score of 78.5. With only one exam remaining in the class, what is the minimum score Carl will need on that exam to have an overall mean of 80?

Question

jamierox4ev3r · Answer

Hey there! So with a mean of 78.5 after 6 exams, what is the sum of his exam scores?

pphalke · Answer

Hey. the mean means to add the numbers and divide but in this case how would  I go about doing that

jamierox4ev3r · Answer

so you would multiply 78.5 by 6. This would give you the total amount of points he has gained.


From there, you can figure out the total amount of points for the seventh exam needed to have a mean of 80

jamierox4ev3r · Answer

We're kind of working backwards in this problem

jamierox4ev3r · Answer

To average 80 over 7 exams, the sum of scores must be (7)(80)=560.

jamierox4ev3r · Answer

@pphalke  making sense so far?

pphalke · Answer

yes its making a lot of sense

jamierox4ev3r · Answer

awesome! Now, we'd take some of the math we did earlier

78.5 x 6 = 471 which is the total amount of points he gained

he needs at least 560 total points in order to have an average of 80

jamierox4ev3r · Answer

so in order to find out what value satisfies this, which two numbers would we subtract from each other? @pphalke

pphalke · Answer

560 and 471 which brings the total to 89%

jamierox4ev3r · Answer

no, not 89%

jamierox4ev3r · Answer

but you did get the subtraction right!

jamierox4ev3r · Answer

you need to get 89 points in order to keep an average of 80%

jamierox4ev3r · Answer

because 560 divided by 7 equals 80.

and that is how you find mean :)

jamierox4ev3r · Answer

does that make sense?