Period 1 has 15 students in it and a test average of 86%. Period 2 has 21 students in it and an average of 88%. Period 3 has 12 students in it and an average of 95%. Use weighted means to find the overall average of the classes.

87.3%
88.7%
89.1%
91%

Question

Period 1 has 15 students in it and a test average of 86%. Period 2 has 21 students in it and an average of 88%. Period 3 has 12 students in it and an average of 95%. Use weighted means to find the overall average of the classes.

 87.3%
 88.7%
 89.1%
 91%

kirbykirby · Answer

$15+21+12=48$
So:$$ \frac{15}{48}(0.86)+\frac{21}{48}(0.88)+\frac{12}{48}(0.95)=?$$ and convert the decimal into percent again