Question

the mean height of the class is 152 cm. the mean height of boys is 158 cm with a standard deviation of 5cm and the mean height of girl is 148 cm with a standard deviation of 4cm find the percent of boys in the class and also sd of height of all the students in a class​

Answer 1

Explanation:

Given mean of 8 students is 152 cm

Recall that, mean = sum of obeservations / Number of observations

152 = sum of obeservations / 8

Hence the sum of observations = 152 × 8 = 1216 cm

Given that two more students of heights 143 cm and 156 cm joined the group.

Hence new sum of observations = 1216 + 143 + 156 = 1515 cm

∴ New mean height = 1515/10 = 15.15 cm