The average height of 30 boys was calculated to be 150 cm. It wdetecte

1.	The average height of 30 boys was calculated to be 150 cm. It wdetected later that one value of 165 cm was wrongly copied as 135 cmfor the computation of the mean. Find the correct mean.
Answer» Given: Average height of 30 students = 150 cm Mean height = (sum of heights of students)/(Number of students) 150 = (sum of heights of students)/(30) Hence, Sum of heights of students = 4500 cm Given: One observation is wrongly copied as 135 cm instead of 165 cm Error in the entering the observation = 165 – 135 = 40 cm Hence, correct sum of heights of students = 4500 +40 = 4540 cm Correct mean height = 4540/30 = 151.33 (nearly)

The average height of 30 boys was calculated to be 150 cm. It wdetected later that one value of 165 cm was wrongly copied as 135 cmfor the computation of the mean. Find the correct mean.

Answer»

Given: Average height of 30 students = 150 cm

Mean height = (sum of heights of students)/(Number of students)

150 = (sum of heights of students)/(30)

Hence, Sum of heights of students = 4500 cm

Given: One observation is wrongly copied as 135 cm instead of 165 cm

Error in the entering the observation = 165 – 135 = 40 cm

Hence, correct sum of heights of students = 4500 +40 = 4540 cm

Correct mean height = 4540/30 = 151.33 (nearly)