PROBABILITY Flashcards
What is probability?
The likelihood of an event happening.
What is the the difference between theoretical and experimental probability?
theoretical is from thinking of all of the possibilities and doing it with math, experimental is the #successes/total attempts you observe.
how do you find “probability”
(# ways you can be successful) / (# total ways possible)
What is the symbol that joins two sets together into one set?
A big U , stands for UNION
What is the symbol that just takes the overlap of two sets?
An upside down U, look like this: ∩, INTERSECTION
What do students forget about OR ?
The OR BOTH part. The union of A and B are all of the elements in A, in B and also the ones that are in BOTH.
Why does OR go with UNION, ex. A U B = A or B
Because you are part of the union as long as you are a part of A or B or BOTH.
Why does AND go with INTERSECTION? A ∩ B = A and B
Because ONLY if you are a member of A and also a member of B, can you be a part of the intersection, A ∩ B
OR goes with______ [union or intersection]
union
AND goes with ______ [union or intersection]
intersection
UNION goes with ______ [OR or AND]
OR
INTERSECTION goes with _____ [OR or AND]
AND
What numbers can represent a probability?
Always between 0 and 1, examples: 0, .75, .05, 1, .35
What fractions can represent a probability?
Any fraction as long as the top is smaller than the bottom (or equal). IT CAN’T BE TOP HEAVY!
Can you have a probability of 3.5?
NO. probabilities are between 0 and 1
can you have a probability of 0.5?
Yes, that’s 50%
can you have a probability of 3/5?
Yes, that’s 60%
can you have a probability of 5/3?
NO… that is more than 1
How can you think of %
PER 100 (or, divided by 100)
If you have 3 pairs of shoes, two pairs of pants and 4 shirts.. how many outfits?
3*2*4= 24 outfits
How many cards in a deck of cards?
52
How many diamonds in a deck of cards?
13
What is the probability of randomly taking one card and getting a diamond from a deck?
13/52 or 1/4
What is the probability of randomly taking one card and getting a king from a deck?
4/52 or 1/13
What is the probability of randomly taking one card and getting a red card from a deck?
26/52 or 1/2
How many kings in a deck of cards?
4
what is the probability of getting 3 tails in a row flipping a coin?
1/2 x 1/2 x 1/2 = 1/8
What does A’ mean?
The elements not in A
If A = { 1, 2 }, how many elements does A have?
two
If A = { 1, 2, 6} , what is n(A) ?
the number of elements in A. In this case, n(A)= 3
Difference between a Permutation and a Combination?
Permutation is choosing and Placing in a Particular Place, Combinations are just choosing
where is the permutation button on the calculator?
Math > PRB then down to nPr
where is the combination button on the calculator?
Math > PRB then down to nCr
if there are 10 kids and you are choosing 3 to bring on a trip, how many ways can you do that?
Combination. nCr with n=10 and r=3
If there are 10 kids and you are choosing a president, vp and treasurer, how many ways can you do that?
Permutation. nPr with n=10 and r=3
With tree diagrams, what does MA.AD stand for?
Multiply across, Add down
What do the probabilities on the branches leaving a single node in a tree diagram have to add to?
- If you have two branches, then they should add to 1, if you have five branches from same node, all five added together should equal 1.
How do you get the probability of taking a certain route on a tree diagram?
multiply the branches along the path till the end. write it at the end of the branch.