The average height of 50 pupils in a class is 150cm. Five of them whose average height is 146 cm, leave the class, and five others whose average height is 156 cm. join. The new average height of the pupils of the class (in cm) is __________.

Correct option is C

Given:

Total number of pupils initially: 50

Average height of these pupils: 150 cm

Five pupils leave, with an average height of 146 cm

Five new pupils join, with an average height of 156 cm

Formula Used:

New Average Height=Total Initial Height−Total Height of Leaving Pupils +Total Height of Joining PupilsTotal Number of Pupils

Solution:

​$$50×150 cm=7500$$​​

5×146 cm=730 cm

5×156 cm=780 cm

7500 cm−730 cm+780 cm = 7550

​$$\frac{7550\,\text{cm}}{50} = 151 cm$$​​

Therefore, the new average height of the pupils in the class is 151 cm.