The weight of 7 boys in a group are 52 kg, 57 kg, 55 kg, 60 kg, 54 kg, 59 kg and 55 kg. Find the mean weight of the group.

Weights of 7 boys (in kg) :

52, 57, 55, 60, 54, 59, 55

Number of boys (n) = 7

Mean = $\dfrac{\text{Sum of observations}}{\text{Total number of observations}}$

Sum of observations = 52 + 57 + 55 + 60 + 54 + 59 + 55 = 392

Total number of observations = 7

Mean = $\dfrac{392}{7}$ = 56.

Hence, mean weight of the group is 56 kg.