Question

there are 100 student in a class the mean height of the class is 150 cm if the mean height of the 60 boys is 70 centimetre find the mean height of the girls in the class​

Answer 1

Answer:

270 cm

(These girls are very tall!  But then, the boys are very short with a mean height of 70 cm.

If the mean height of boys was meant to be 170 cm, then follow the same process with the necessary changes and you will get the mean height of girls to be 120 cm.  Maybe this is the question (and answer) that was intended?)

Step-by-step explanation:

Let the mean height of the girls be m.

There are 100 - 60 = 40 girls.  So:

   ( sum of girls' heights ) / 40 = m

=> sum of girls' heights = 40m

Similarly, the mean height of the 60 boys is 70cm, so:

   ( sum of boys' heights ) / 60 = 70 cm

=> sum of boys' heights = 4200 cm

As the average height of the 100 students is 150 cm,

   ( sum of all students' heights ) / 100 = 150 cm

=> ( sum of boys' heights ) + ( sum of girls' heights ) = 15000 cm

=> 4200 cm + 40m = 15000 cm

=> 40m  =  15000 cm - 4200 cm  =  10800 cm

=> m = ( 10800 / 40 ) cm

=> m = 270 cm