The mean mass of 8 boys is 55 kg and the mean mass of a group of girls is 52 kg.The mean mass of all the children is 53.2 kg. How many girls are there?
B = number of boys = 8 G = number of girls The average mass of everyone is: [ (55)B + (52)G ] ⁄ (B + G) = 53.2 (55)B + (52)G = (53.2)B + (53.2)G (1.8)B = (1.2)G (1.5)B = G The ratio of girls to boys is —> 1.5 :1 If there are 8 boys, then there are 12 girls
