Correct Answer - Option 1 : 76 kg
Given:
Average weight of 25 students of a class is 50 kg.
New average is increased by 1 kg.
Formula used:
Average = (Sum of total observations)/(Total number of observation)
Calculation:
Let the weight of teacher be 'x' kg.
(Sum of total observations) = average × (Total number of observation)
⇒ Total weight of all student = 50 × 25 = 1250 kg
New average = 50 + 1 = 51
New observation when teacher included = 25 + 1 = 26
So, Total weight of all = 51 × 26 = 1326 kg
The weight of the teacher = (Total weight of all) – (Total weight of all student)
⇒ The required weight = 1326 – 1250 = 76 kg
∴ The weight of the teacher is 76 kg.