Robert claims that his dog can do single digit multiplication. He shows the dog 8 cards with simple multiplication problems that
are either correct or incorrect. The dog correctly identifies the correctness of the card 5 times out of 8. If the dog were simply guessing, how many would the dog be expected to get correct?
05
08
13
04
There are two possibilities: correct and incorrect. To the dog, these answers are both equally valid, since he does not actually know multiplication. So, correct and incorrect have an equal probability. This means that the dog is estimated to get about half of the questions right.
Therefore, he will get 8/2=4 of the questions correct.
