Heuristics to highlight

Use suitable numbers (instead of algebra), Guess-and-Check, Divide into cases, Work backwards.

a)         A boy claims that when he left school X and joined school Y, he raised the average IQ of both schools. Explain if this is possible.

b)        A striker in football is rated according to the average number of goals he scores in a game. Wayne had a higher average than Carlos for games in the year 2007. He also had a higher average than Carlos for games in the year 2008. Can we say that Wayne is a better striker than Carlos over the years 2007-2008?