The average for the math test is 9.8. If we do not count the lowest grade of 5, on this test, the average will be 10. what is the number of students in the class

If we denote the number of students by n , the total sum of all grades is 9.8n . When we exclude the lowest grade of 5, the number of students lowers to n-1 , and the new sum is 9.8n - 5 . With the new average being 10, we can write the equation:

10(n-1) = 9.8n - 5 .

Solving for n :

10n - 10 = 9.8n - 5 ,

10n - 9.8n = 10 - 5 ,

0.2n = 5 ,

n = \frac{5}{0.2} ,

n = 25 ,

n = 25 ,

Hence, the number of students in the class is n=25 .