Four children made the following statements.
Gavin : Ellie is 2 kg heavier than Sebastian.
Sebastian : Our masses are in consecutive order.
Isaiah : The average of Gavin's mass and my mass is 41 kg.
Ellie : I am the heaviest.

What is the total mass of Isaiah, Ellie and Gavin ?
Order of the mass of 4 children:
_____ , Sebastian, _____ , Ellie (Heaviest)

Total mass of Isaiah and Gavin
= 2 x 41
= 82 kg

For Isaiah and Gavin,
Mass of the lighter one = 1 u
Mass of the heavier one = 1 u + 2

Total mass of Isaiah and Gavin
= 1 u + 1 u + 2
= 2 u + 2

2 u + 2 = 82
2 u = 82 - 2
2 u = 80

1 u = 80 ÷ 2 = 40

The mass of the four children in consecutive order is 40, 41, 42 and 43.

Total mass of Isaiah, Ellie and Gavin
= 40 + 42 + 43
= 125

Answer(s): 125 kg