Heads or tails?
Rick wanted to go to the movies and Gayle wanted to go swimming. They
decided to toss a coin to see which they would do.
“You call it,” said Rick as he flipped the coin.
“Tails never fails!” called Gayle. And sure enough, the coin landed with
the tails side up. “See,” grinned the girl. “I told you that ‘tails
never fails!’ Swimming it is!”
Do you think that Gayle is right? Do you think that tails will win more
often than heads? Oi’ do you think heads is usually the winner?
Try an experiment. Draw a line down the middle of a piece of paper. At
the top of the paper, on one side of the line, write “Heads.” On the
other side, write “Tails.” Then, flip a coin fifty times. Each time it
comes up heads, make a mark under “Heads” on the paper. If it comes up
tails, make a mark under “Tails.”
After you’ve tossed the coin fifty times, count the marks under “Heads”
and “Tails.” You’ll find that they’re almost even. There may be a few
more heads, or a few more tails, but chances are there will only be two
or three more of one than the other. And, if you flip the coin another
fifty times, you’ll find the results will be nearly the same.
When you flip a coin, the chance that it will come up heads is exactly
the same as the chance that it will come up tails. You can’t count on
heads coming up more often than tails, or tails more often than heads.
But suppose you do get ten heads in a row, what then? On the eleventh
throw, are you more likely to get another head or a tail? The chance
that the coin will come up tails is still exactly the same as the chance
that it will come up heads. Nothing has changed, as you’ll find out if
you flip the coin a few more times.
