elsa has scored 80, 66, 86, 84, and 79 on her previous five tests. what score does she need on her next test…

Explanation:

Step1: Recall the mean formula

The mean $\bar{x}=\frac{\sum_{i = 1}^{n}x_{i}}{n}$, where $n$ is the number of data - points and $\sum_{i = 1}^{n}x_{i}$ is the sum of the data - points. Here, $n = 6$ (5 previous tests + 1 next test), and $\bar{x}=78$.

Step2: Calculate the sum of the first five scores

The sum of the first five scores $S_5=80 + 66+86 + 84+79=395$.

Step3: Let the score on the sixth test be $x$.

The sum of all six scores $S_6=S_5 + x=395 + x$.

Step4: Use the mean formula to solve for $x$.

Since $\bar{x}=\frac{S_6}{6}$ and $\bar{x}=78$, we have $78=\frac{395 + x}{6}$. Cross - multiply: $78\times6=395 + x$. So, $468=395 + x$.

Step5: Solve for $x$.

Subtract 395 from both sides: $x=468 - 395=73$.

Answer:

73