Question

The mean height of 10 students is 151.8cm. Two more student of heights 157.6cm and 154.4 cm join the group. What is the new mean height?

Answer 1

Hey mate..!

Mean = sum of all observations /Total no: of observations.
Sum of all observations = Mean × Total no: of observations.
= 151.8 cm × 10 = 1518 cm
157.6 cm and 154.4 cm are the new heights .So to find the new mean, these two heights must be added and the total no: of students thus is equal to 12 students.(as 2 students were added)
New sum of observations = 1518 cm + 157.6 cm + 154.4
= 1830 cm

New mean = sum of all observations /Total no: of observations.
= 1830 cm ÷ 12 = 152.5 cm

Answer 2

Mean = sum of all observations /Total number of observations.

Sum = Mean × Total number of observations.

= 151.8 cm × 10 = 1518 cm


Heights of the two new students (157.6cm and 154.4cm )must be added along with +2 in Number of observations 


New sum of observations = 1518 cm + 157.6 cm + 154.4= 1830 cm

New Mean = Sum of all Observations / Total number of observations= 1830 / 12
= 152.5 cm