Okay I am having trouble setting up this math word problem.

In Mr. Black's class 20 people took a biology test and had an average of 88%. Two more took the test later and made an average of 55% What is the average of the entire class?

Also, I have gotten an answer for this one but not sure if it is right so I guess how do you set this one up:

When 100 students took a test the average score was 77.1 Two more students took the test. The sume of their scores was 125. What is the new average?

2. For #1:

so 88% counts for (20/22)*100 % of the mark in the class. Then, 55% counts for (2/22)*100 % of the mark. You want to multiply those portion percentages by the percentage of the class that created those averages respectively
55* ((2/22)*100 % and 88*...... (you fill in the rest on that one) then add them together.

This is at least how we would calculate our marks in our high school, and we are marked on varying assignments that are worth differnt percentages which seems to be similar to the scenario here. Anyone else correct me if I'm wrong.

3. Originally Posted by Mathhelp!
When 100 students took a test the average score was 77.1 Two more students took the test. The sume of their scores was 125. What is the new average?
how do we get the average scores? we sum all the scores and divide by the number of students.

Hint: if two more students are added, it means the number of students is now 102. the sum of their scores is added to the old sum of scores. so what would the average be?