g = number of girls
b = number of boys
SG = Sum of height of all girls
SB = Sum of height of all boys
There are 45 studentss in the class.
g = 45 - b
The mean height of girls:
Sum of height of all girls / g = 144
SG / g = 144
SG = 144 ∙ g
SG = 144 ∙ ( 45 - b )
SG = 6480 - 144 b
The mean height of boys:
Sum of height of all boys / b = 168 cm
SB / b = 168
SB = 168 b
The mean height of 45 students is 152cm.
( SG + SB ) / 45 = 152
( 6480 - 144 b + 168 b ) / 45 = 152
6480 + 24 b = 45 ∙ 152
6480 + 24 b = 6840
24 b = 6840 - 6480
24 b = 360
b = 360 / 24
b = 15
g = 45 - b = 45 - 15 = 30
There are 30 girls and 15 boys in the class.
The mean height of 45 students is 152cm. If the mean height of girls alone is 144cm and that of boys alone is 168cm. Find the number of boys and girls in the class
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