Question

cameron took 4 tests, and his scores were as follows: 100, 60, 80, and 30. cameron took another test that was scored x. the mean score of the 5 tests he took is 72. what is the value of x? a. 54 b. 67.5 c. 68.4 d. 90

Explanation:

Step1: Recall mean formula

The mean $\bar{x}=\frac{\sum_{i = 1}^{n}x_{i}}{n}$. Here, $n = 5$ and $\bar{x}=72$, and the scores are $100,60,80,30,x$. So, $72=\frac{100 + 60+80 + 30+x}{5}$.

Step2: Simplify the equation

First, calculate the sum of the known scores: $100+60 + 80+30=270$. The equation becomes $72=\frac{270 + x}{5}$.

Step3: Solve for x

Multiply both sides of the equation by 5: $72\times5=270 + x$. So, $360=270 + x$. Then subtract 270 from both sides: $x=360 - 270=90$.

Answer:

D. 90