How do you spell heavier?
That is the correct spelling of the comparative adjective "heavier" (having greater weight).
Which is heavier 8 marbles that are exactly alike except that one of them is slightly heavier than the others I then give you a balance scale and ask you to determine the heavier marble in 3 weighings?
Weighing 1: Weigh any four against any other four. The set containing the heavier marble will be heavier. Weighing 2: Weigh any two from this heavier set against the other two from the set. The pair containing the heavier marble will be heavier. Weighing 3: Weight the two marbles from the heavier pair against one another and you have the odd marble. Simple!