Answer:
75.5
Step-by-step explanation:
To calculate the mean we use
mean = [tex]\frac{score}{count}[/tex]
To calculate the mean for class B we require their score
Using the mean for class A
[tex]\frac{score}{25}[/tex] = 67.8 ( multiply both sides by 25 )
score = 67.8 × 25 = 1695
Similarly using the mean for all 55 students
[tex]\frac{totalscore}{55}[/tex] = 72 ( multiply both sides by 55 )
total score = 72 × 55 = 3960
Hence score for class B = 3960 - 1695 = 2265
mean for class B = [tex]\frac{2265}{30}[/tex] = 75.5
