The average height of two men J and K is 171 cm. Another man L joins them and the average height becomes 166 cm. If another man M whose height is 21 cm more than that of L replaces J, then the average height of K, L and M becomes 161 cm. What is the height of J?

What is the average number of students in B.Tech (220), M.Tech (140), and B.A (4344) courses together?

A class has two sections A and B, which have 36 and 44 students respectively. If the average weight of section A is 40 kg and that of section B is 35 kg, find the average weight of the whole class.