The vast majority of people say 10 cents. The answer is 5 cents. Our intuition tells us that the ball costs 10 cents. 

Why does this error occur? Mode 2 is lazy and the Fast Mode kicks in automatically with the incorrect answer – you need algebra to get the correct answer – the slow mode needs to be engaged with visual thinking: 

                    ?+(100+ ?)=110 

                    2 ?+100=110 

                    2 ?=10 

                    ?=10÷2 

                    ?=5