For The Love of Calculators!Probability puzzles require you to weigh all the possibilities and pick the most likely outcome.
Little Billy has a calculator with 15 buttons. He has 10 keys for 0-9, a key for addition, multiplication, division, and subtraction. Finally, he has an = sign. However, Mark the Meanie messed up the programming on Billy's calculator. Now, whenever Billy presses any of the number keys, it comes up with a random single-digit number. The same goes for the four operations keys (+,-,x, /). So whenever Billy tries to press the + button, the calculator chooses randomly between addition, multiplication, subtraction, and division. The only key left untouched was the = sign.
Now, if Billy were to press one number key, one operation key, then another number key, then the = button, what are the chances the answer comes out to 6?
HintThink about how many ways he could possibly get 6.
AnswerThere is a 4% chance.
There are 16 possible ways to get 6.
There are 400 possible button combinations.
When Billy presses any number key, there are 10 possibilities; when he presses any operation key, there are 4 possibilities.
16 working combinations/400 possible combinations= .04 or 4%
See another brain teaser just like this one...
Or, just get a random brain teaser
If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.
Back to Top