Probability
Probability - How likely something is to happen.
Many events (outcomes) can't be predicted with total certainty. The best we can
say is how likely they are to happen, using the idea of probability.
In general:
Probability of an event happening =
𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑤𝑎𝑦𝑠 𝑖𝑡 𝑐𝑎𝑛 ℎ𝑎𝑝𝑝𝑒𝑛
𝑡𝑜𝑡𝑎𝑙 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠
Example: the chances of rolling a "4" with a die
Number of ways it can happen: 1 (there is only 1 face with a "4" on it)
Total number of outcomes: 6 (there are 6 faces altogether)
So the probability =
1
6
Theoretical vs. Experimental Probability:
Theoretical probability is what you expect to happen,
but it isn’t always what actually happens.
Experimental probability is what actually happens instead of
what you were expecting to happen.
Example:
Imagine that you toss a coin 20 times. How many times would you expect it to land
on heads? You might say, 50% of the time, or half of the 20 times. So you would
expect it to land on heads 10 times. This is the theoretical probability. The
experimental probability will be what actually happens after all 20 tosses.
Practice:
There are 9 dogs at the dog park on a busy Saturday. 3 of them are
dachshunds. What is the probability that a randomly selected dog is a
dachshund?
Probability – continued