All AP Statistics Resources
Example Questions
Example Question #31 : Probability
Automobile license plates in a certain area display three letters followed by three digits, and the letters Z and N are not used. How many plates are possible if neither repetition of letters nor of numbers is allowed?
None of the other answers
If no letters are to be repeated and the letters Z and N are not used, then there are possible 3-letter combinations. If no digits are to be repeated, then there are possible 3-digit combinations. Multiply these two results together, and you get a total of 8,743,680 possible license plates .
Example Question #11 : How To Use The Multiplication Rule
Tina and her 2 close friends are going to get together to see a movie Friday night, and Tina wants to determine the probability that they will all want to see the same one. There are 6 movies playing in the local theater, so the friends each wrote down the name of the movie they want to see. (They are all appealing movies that and have an equal chance of being chosen.)
What is the probability that all 3 girls will choose the same movie out of the 6 playing?
When determining the probability of independent events, you multiply the probability of each event occurring.
The probability of a single girl choosing a specific movie is 1 out of 6, so to find the probability of this happening the same 3 times, you multiply 1/6 three times:
Example Question #32 : Probability
Mike's five-person family is going out to dinner, and each person is planning to order a soda. The restaurant offers Soda1 and Soda2 only, and each family member likes both sodas equally.
What is the probability that all 5 family members will order Soda1?
When determining the probability of several events occuring independently, you use the multiplication rule, meaning that you multiply the probability of each individual event occuring.
In this problem, the events are independent, meaning that each person's soda order does not affect the probabilty of someone else's order.
The probability of one person choosing Soda1 is 1 out of 2, or .
The probability of all five people ordering Soda1 is:
Example Question #34 : Statistical Patterns And Random Phenomena
Jenna and her two sisters are all picking a random number from 1 to 10.
What is the probability that they will all choose the same number?
When determining the probability of several events occuring independently, you use the multiplication rule, meaning that you multiply the probability of each individual event occuring.
In this problem, the events are independent, meaning that each person's number choice doesn't impact the other person's number choice
The probability of one person choosing a specific number is .
The probability of all 3 people choosing the same specific number is:
Example Question #31 : Probability
A person rolls a single 6 sided dice. What is the probability they will roll a 2 or a 4?
In a single roll of a dice, rolling a 4 is mutually exclsuve of getting a 2. Therefore we will use the addition rule to find the probability of getting a 2 or a 4.
First, find the probability of each seperate event.
Because the problem asks for the probability of a 2 "or" a 4, we will add the probability of each event.
Example Question #31 : Statistical Patterns And Random Phenomena
A tutoring agency helps match tutors with students. The agency knows that percent of all the tutors it places with students will leave the position within a year, but after the first year, only percent of the tutors who stay on will leave. At the start of the school year, an elementary school hires tutors from the agency, then the next year it hires more. How many of the tutors are expected to still be working with their assigned students at the end of the second year?
If the school starts with tutors, it can expect to still be tutoring at the end of the first year. After that, we expect only percent or tutors to leave. So at the end of the second year, there will be the original tutors hired the at the start of the first year and the remaining tutors who were hired at the start of the second year. .
Example Question #31 : Probability
If you have a deck of cards, what is the probability that you draw a spade after you drew a non-spade on the first draw without replacement?
You must use the multiplication rule which is the probability of one event happening after one has already taken place is the product of both probabilities. The probability of drawing a non-spade on the first draw is . Since there is no replacment, there are now 51 cards in the deck. The probability of drawing the spade on the second draw is . The probability of both happening after one another is then =
Example Question #31 : Probability
Charlene has 7 blue chips, and Karen has 5 green ones. They decide to mix them up in a bag, then Karen will pick 5 chips and Charlene gets the rest.
What is the likelyhood Karen ends up with 5 chips of the same color?
There are 2 ways Karen gets 5 chips of the same color: she gets all 5 greens, or 5 blues. there is only 1 way to get all 5 greens: probability of which can be calculated as;
to calculate p(allblue) we use:
since order doesn't matter and chips are being drawn without replacement, this is an acceptable calculation and summing them yields
Example Question #32 : Probability
A ninja is training for his super secret mission, throwing grappling hooks at targets ft away. He has determined over the last practice session, that he makes his shot roughly % of the time. What is the maximum number of shots the ninja will need to take to have a % chance of hooking his grapnel?
Total likelihood of making the shot = sum of likelihood of making 1st shot+2nd shot+...
1st shot=
2nd shot=.
3rd shot=
4th=
5th=
6th=
Example Question #33 : Probability
Frank of the forest is a monkey man who was raised by chimpanzees from a very young age. He enjoys swinging with his monkey friends. When Frank jumps from one tree to another, the chance that he falls increases by 10% for every foot he jumps past his armspan of 3 feet. (he has a 10% chance of falling at 4ft)
One day, Frank watches his monkey friends do jumps, one ft, one ft, another ft, one ft, a ft jump, another two ft jumps, and then a ft jump
Frank knows from experience not to take a jump route if the likelihood of him falling goes above %. At what point in this -jump route should Frank stop and rest?
Frank can finish this route, none of the jumps have above a % chance of falling
After jumps, before the two ft jumps
After jumps, before the ft jump
After jumps, before the last ft jump
After jumps, before the ft leap
After jumps, before the last ft jump
This is multiplication rule. let's calculate the chance frank doesn't fall.
For the first jump this is , the first two is , first 3: , first 4:, first 5:, first 6:, first 7:.
Since the 7th jump drops his survival rate below % (his fall rate above 60%) we would caution Frank to stop after his 6th jump, even if the 7th jump isn't that far
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