Question

In a class of 30 students, 2 students have yet to take the test. So far, the class average is 82%. What must these 2 students average in order to bring the class average to an 83%?

Answer 1

i believe either 84 or 85

Answer 2

you can figure it out.

you have the average test score for 28 of the students

that means you know
(t1+t2+t3+.....+t28)/28 = 82

where t1,t2, etc are their test scores.
if we call the sum T
that is T= (t1+t2+t3+.....+t28)
we have T/28= 82
multiply both sides by 28 to get
T= 28*82

now if we add 2 more scores and divide by 30, we get the new average
(T+t29+t30)/30 =83
or
T + (t29+t30)= 30*83
now subtract T from both sides
(t29+t30)= 30*83- T
but T is 28*82, so we get
(t29+t30)= 30*83-28*82

if we divide the left side by 2, we get the average of the last two tests
of course, we must divide the right side by 2 to keep things an equation:
(t29+t30)/2 = (30*83-28*82)/2
AVG= (30*83-28*82)/2

Answer 3

thank you!