The grade 3 and 4 students in Spruce Glen Public School had to write a quiz. The bar chart below shows the results of the quiz. Reading the grades from left to right in the bar chart, we see the grades from lowest to highest. In other words, **C-** is the lowest grade and **A+** is the highest grade.

How many students wrote the quiz?

What is the median of all the grades on this quiz? The median is the middle value of the data when arranged in order.