A professor has recorded exam grades for 10 students in his class, but one of the grades is no longer readable. If the mean score on the exam was 80 and the mean of the 9 readable scores is 84, what is the value of the unreadable score?

The value of the unreadable score is 44.

Step-by-step explanation:

The mean is the sum of all the exams' scores divided by the number of exams. So

In which S is the sum of all the exams's scores and N is the number of exams.

In this problem, we have that:

10 students, so N = 10.

9 readable scores have a mean 84, there is also one unreadable score, so

Mean of 80, so M = 80.

We want to find x

The value of the unreadable score is 44.

proofs involving isosceles triangles often require special consideration because an isosceles triangle has several distinct properties that do not apply to normal triangles.(more about triangle types) therefore, when you are trying to prove that two triangles are congruent, and one or both triangles, are isosceles you have a few theorems that you can use to make your life easier.

step-by-step explanation:

an isosceles triangle has two congruent sides and two congruent angles. the congruent angles are called the base angles and the other angle is known as the vertex angle. ∠bac and ∠bca are the base angles of the triangle picture on the left. the vertex angle is ∠abc