The average height of 20 girls out of a class of 50 is 142 cm. and that of the remaining girls is 149 cm. The average height of the whole class is :  Choose the correct choice
A) 146.2 cms	B) 146.5 cms	C) 146.9 cms	D) 142.2 cms	E) 136.2 cms
Explanation:   146.2 cmsverage height of the whole class =(20×142+30×149/50)=146.2 cms   146.2 cmsnswer 146.2 cms
<result>A</result>
The average height of 20 girls out of a class of 50 is 142 cm. and that of the remaining girls is 149 cm. The average height of the whole class is :