Question

A student has scores of 56.25, 57.5, and 62 on his first three tests. He needs an average of at least60 to earn a grade of D. What is the minimum score that the student needs on the fourth test toensure a D?Note: The answer need not be an integer.

Answer 1

From the information provided, the student has achieved three of the required scores and the fourth when added would be used to calculate an average of 60. To calculate the average, the student would use the following approach;

`\text{Average}=\frac{\text{Sum of all scores}}{Number\text{ of tests}}`

We shall take the unknown test to be x (that is, the fourth test), and then we would have;

`\begin{gathered} \text{Average}=(56.25+57.5+62+x)/(4) \\ Note\text{ that the average score should be at least 60.} \\ Therefore; \\ (56.25+57.5+62+x)/(4)\ge60 \\ (175.75+x)/(4)\ge60 \\ \text{Cross multiply and you'll have;} \\ 175.75+x\ge60*4 \\ 175.75+x\ge240 \\ \text{Subtract 175.75 from both sides;} \\ x\ge64.25 \end{gathered}`

ANSWER:

The minimum score on the fourth test would be at least 64.25 to obtain a grade of D