The mean height of 36 students of a class is 150.5 cm. Later on, it was detected that the height of one student was wrongly copied as 165 cm instead of 156 cm. Find the correct mean height.

By formula,

Mean = $\dfrac{\text{Total height}}{\text{No. of students}}$

Given,

Mean height of 36 students of a class = 150.5 cm

$\therefore 150.5 = \dfrac{\text{Total height}}{36} \\[1em] \text{Total height} = 150.5 \times 36 \\[1em] = 5418 \text{ cm}.$

As, height of one student was wrongly copied as 165 cm instead of 156 cm.

∴ Actual total height = 5418 – 165 + 156 = 5409 cm.

Actual Mean height = $\dfrac{5409}{36}$ = 150.25

Hence, the correct mean height is 150.25 cm.