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In a class in which the final course grade depends entirely on the average of four equally weighted 100-point tests, Joyce has scored 90, 93, and 85 on the first three. What range of scores on the fourth test will give Joyce a C for the semester (an average between 70 and 79, inclusive)? Assume that all test scores have a non-negative value.

Express your answer in interval notation.


HELP ASAP BRAINLEST AND THANKS

Respuesta :

madethisfortwitch1

Answer:

[12,48]

Step-by-step explanation:

We will start by calculating the score she needs to get a 70 in the class

We will let x equal the fourth test

[tex]\frac{90+93+85+x}{4} =70[/tex]

This isn't hard to solve and we will do so by multiplying 4 by both sides and subtracting 268 (90+93+85)

This means that x= 12

We will then use the same formula but set it equal to 79

[tex]\frac{90+93+85+x}{4} =79[/tex]

We solve x in the exact same way and get x=48

our final answer is now [12,48]

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