Question

Maria's first four test scores were 60, 90, 90, and 70. What what does she need to make on the fifth test to maintain a 70 average?

Answer 1

A 40 is the lowest she can make and that would give her exactly a 70 average. 

Answer 2

She needs to get a score of 40 on the fifth test to maintain a 70 average

Explanation:

The idea is to calculate an average among the scores. The formula is the sum of all scores divided between the number of scores.

`average = (sum\, of\, scores)/(number\, of\, scores)`

First step

If the idea is to include a fifth score to maintain an average of 70, it should be included in the equation as a variable x. According to the previous equation:

`70 = (60+90+90+70+x)/(5)`

The next step is to find x.

`x = (70)* (5) - (60+90+90+70) = 40`

Conclusion

Hence, she needs to get a score of 40 on the fifth test to maintain a 70 average.