The average height of 40 girls out of a class of 50 is 169 cm. and that of the remaining girls is 167 cm. The average height of the whole class is :	Pick.
A) 138.9 cms B) 149.2 cms C) 168.6 cms D) 159.2 cms E) 142.5 cms
Explanation:   Average height of the whole class =(40×169+10×167/50)=168.6 cms   Answer 168.6 cms
<result>C</result>
The average height of 40 girls out of a class of 50 is 169 cm. and that of the remaining girls is 167 cm. The average height of the whole class is :