To answer this question, we need to use the linear equation:
We all know that to get the average using the mean, we add all the terms and then, divide it by the number of terms.
Okay, let x be the least score she can make in the 4th quiz:
The symbol "
" means at least and
means at most.
Okay, we add terms that can be added, so we first add 81, 76, and 82.
We multiply 4 to both sides to cancel the denominator
80 x 4 =320
So, it is:
239 + x
We subtract 239 to both sides so that only thing that will be left in "239 + x" is only "x."
239 + x - 239
320 - 239
Therefore, the least score she can make on the 4th quiz is 81.