Mean weight of 34 students = 42 kg. Total weight of students = 34 × 42 = 1,428 kg. Mean weight increased = 42 kg + 400 g = 42.4 g Total weight of 35 persons including the teacher = 42.5 × 35 = 1,484 kg Weight of the teacher = Total weight including the teacher -Total weight of the students Weight of the teacher = 1,484 - 1,428 = 56 kg.