Question

1-5 Skills Practice

Descriptive Modeling and Accuracy
1. TEST SCORES A teacher compares the ratio of the number of questions answered correctly to the
total number of questions on a test as a metric. For a student to earn and A or B on a test, the ratio
must be greater than or equal to 0.8. The last test given by the teacher had a total of 40 questions.
Using this metric, what is the least number of questions a student can answer correctly and earn an
A or B on the test?
number of questions answered correclty
Ratio to earn an A or B - -
number of questions

Answer 1

The least number of questions a student can answer correctly is 32

Explanation:

Let

x -----> the number of questions answered correctly

y ----> the total number of questions on a test

`ratio=(x)/(y)`

we know that

For a student to earn and A or B on a test, the ratio must be greater than or equal to 0.8

so

`(x)/(y) \geq 0.8`

For y=40 questions

Find the value of x

substitute

`(x)/(40) \geq 0.8`

solve for x

Multiply both sides by 40

`x \geq 0.8(40)`

`x \geq 32`

so

The least number of questions a student can answer correctly is 32

Verify the ratio

For x=32, y=40

`(32)/(40)=0.8`

Compare

`0.8 \geq 0.8` ----> is ok