In this question, each star equal to 4 students. If the people on 85 and 90 take the test again that means their number should be 14+4 people= 18 people.
If they all get 95, then it means we need to add 18 people to the 95 graph. The number of stars would be: 18 people / (4people/stars)= 4.5 stars
If you add the stars graph it will be easier. It should be clear that 85 will have 1 stars and 90 have 3.5 stars. Adding them up will be 1 stars + 3.5 stars= 4.5 stars
