Question

To earn a B in your algebra course, you must achieve an unrounded test average between 84 and 86, inclusive. You scored 86, 85, and 80 on the first three tests of the grading period. What possible scores can you earn on the fourth and final test to earn a B in the course?
Between 70 and 79
Between 85 and 93
Between 87 and 95
Between 75 and 82

Answer 1

Answer:

Between 85 and 93

Step-by-step explanation:

Remember that average is calculated by adding up the elements of a data set and then dividing the sum by the amount of elements in the set. If your final test score is x, we can write the following double inequality:

$84\leq \frac{86+85+80+x}{4} \leq 86\\84\leq \frac{251+x}{4} \leq 86\\336\leq 251 + x\leq 344\\85\leq x\leq 93$