Question

The average height of 30 girls out of a class of 40 is 160 cms and that of the remaining girls is 156 cms.the average height of whole class is

Answer 1

The average height of whole class is 159 cms.
Sum of height of 30 girls is 4800
Sum of height of 10 girls is 1560
so avg. of whole class= (4800+1560)/40 =159

Answer 2

Find the sum of the height of the 30 girls:

Average = 160 cm

Sum = 160 x 30 = 4800 cm

Find the sum of the height of the remaining 10 girls:

Average = 156 cm

Sum = 156 x 10 = 1560 cm

Find the total height of the 40 girls:

Total height = 4800 + 1560 = 6360 cm

Find the average height of the 40 girls:

Average height = 6360 ÷ 40 = 159 cm

Answer: The average height of the whole class is 159 cm