margie's course in her first three test in algebra are 8668 and 79 what is core mushy abstain on the fourth test to get an average of 78
Answers
Answer:
The grade that she needs to get for the fourth test is 79.
Step-by-step 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}
x
ˉ
=
n
∑
i=1
n
x
i
.
Steps in Solving the Needed Grade
1. Assume a variable for the unknown grade.
2. Substitute the value of \bar{x}=78
x
ˉ
=78 into the formula.
3. Do cross multiplication.
4. Apply the inverse operation to solve for the unknown variable.
Solution:
Let xx be the needed grade.
\begin{gathered}\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}\end{gathered}
x
ˉ
78
78
78(4)
312
312−233
79
=
4
86+68+79+x
=
4
86+68+79+x
=
4
233+x
=233+x
=233+x
=233−233+x
=x