Margie Has Grades 86 68 And 79 In Her First Three Tests In Algebra What Grade Must She Obtain In The Fourth Test To Get An Average Of 78

Margie has grades 86 68 and 79 in her first three tests in algebra what grade must she obtain in the fourth test to get an average of 78

 

Answer:

The grade that she needs to get for the fourth test is 79.

Further Explanation

The process of solving this problem is quite easy. We can apply the concept in Statistics in this matter.

In Statistics, statistician needs to consider the middle value or the measures of central tendency of the given data.

Measures of Central Tendency

1. The mean or average

2. The median

3. The mode

In this problem, we are going to use the mean since the problem is talking about average. The formula for the mean is  \bar{x}=\frac{\sum_{i=1}^{n}x_i}{n}.

Steps in Solving the Needed Grade

1. Assume a variable for the unknown grade.

2. Substitute the value of \bar{x}=78 into the formula.

3. Do cross multiplication.

4. Apply the inverse operation to solve for the unknown variable.

Solution:

Let x be the needed grade.

                                     \begin{aligned}\bar{x}&=\frac{86+68+79+x}{4}\\78&=\frac{86+68+79+x}{4}\\78&=\frac{233+x}{4}\\78(4)&=233+x\\312&=233+x\\312-233&=233-233+x\\79&=x\end{aligned}

Base on the solution process above, it clearly says that to reach the average grade of 78, Margie has to get 79 for the fourth test.

#LearnWithBrainly

To learn another example about grade average, go to brainly.ph/question/1202657

To verify the meaning of each measure of central tendency, click brainly.ph/question/2671306

To one example in solving equation, access the link brainly.ph/question/233609


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