A condition shrinks the group you are choosing from. Once you know the student takes Spanish, the only ones left in the running are the Spanish students, so that count becomes the new denominator.
Also taught in Geometry and Statistics, each at its own level and with its own examples.
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Pick more than one for a sheet that mixes them.
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Of the 21 travelers asked, 11 bring a laptop and, of those, 6 also check a bag. Find the probability that a traveler checks a bag given that they bring a laptop.
There are 29 students in a study. Of them, 12 take Spanish but do not take art, 6 take art but do not take Spanish, and 7 take both. Find the probability that a student takes art given that they take Spanish.
In a group of 30 gardeners, 16 grow tomatoes and, of those, 8 also grow peppers. Find the probability that a gardener grows peppers given that they grow tomatoes.
A survey of 30 employees found that 14 drive to work, 22 work from home some days and 10 do both. Find the probability that an employee drives to work given that they work from home some days.
A survey of 13 students found that 5 belong to the robotics club and, of those, 2 also belong to the debate team. Find the probability that a student belongs to the debate team given that they belong to the robotics club.
There are 15 commuters in a study. Of them, 2 take the bus but do not ride a bike, 3 ride a bike but do not take the bus, and 6 do both. Find the probability that a commuter takes the bus given that they ride a bike.
In a group of 18 students, 8 bring lunch from home and, of those, 5 also buy a drink at school. Find the probability that a student buys a drink at school given that they bring lunch from home.
Find a conditional probability from a two-way table
Of the 21 travelers asked, 11 bring a laptop and, of those, 6 also check a bag. Find the probability that a traveler checks a bag given that they bring a laptop.116
There are 29 students in a study. Of them, 12 take Spanish but do not take art, 6 take art but do not take Spanish, and 7 take both. Find the probability that a student takes art given that they take Spanish.197
In a group of 30 gardeners, 16 grow tomatoes and, of those, 8 also grow peppers. Find the probability that a gardener grows peppers given that they grow tomatoes.21
A survey of 30 employees found that 14 drive to work, 22 work from home some days and 10 do both. Find the probability that an employee drives to work given that they work from home some days.115
A survey of 13 students found that 5 belong to the robotics club and, of those, 2 also belong to the debate team. Find the probability that a student belongs to the debate team given that they belong to the robotics club.52
There are 15 commuters in a study. Of them, 2 take the bus but do not ride a bike, 3 ride a bike but do not take the bus, and 6 do both. Find the probability that a commuter takes the bus given that they ride a bike.32
In a group of 18 students, 8 bring lunch from home and, of those, 5 also buy a drink at school. Find the probability that a student buys a drink at school given that they bring lunch from home.85
Find a conditional probability from a two-way table
Of 20 students taking Spanish, 8 also take art. Find the probability a student takes art given they take Spanish
The condition limits us to the 20 Spanish students.
8 of those take art.
The answer is 52.
Where students go wrong
Dividing by the whole group instead of the group the condition names. Given that they take Spanish, the denominator is the number of Spanish students, not the total.
Also called probability of A given B, dependent probability or two-way table probability.
What you can put on this worksheet
Probability of A given B
In a group of 19 employees, 10 drive to work and, of those, 5 also work from home some days. Find the probability that an employee works from home some days given that they drive to work.→ 21
Yes. Every conditional probability sheet is free to print and free to download as a PDF. There is no account to make, no email to hand over and no limit on how many you take.
Yes. The answer key prints on a second page, and you can choose whether it shows each question beside its answer or just the answers in a list.
Yes. Print straight from the page, or download the PDF and print that. The sheet is laid out for paper rather than squeezed off a screen, so there is room to work under each question, and the answer key comes out on its own page.
Algebra 2 is usually taken around 10th or 11th grade, though schools vary and plenty of students meet it earlier or later. Pick the difficulty rather than the grade: the easy level suits a first lesson on it, the hard level suits review before a test.
Yes, as many as you like. The questions are built fresh each time rather than picked from a fixed set of files, so pressing Generate gives a new sheet. That is what you want for a second class, a retake, or two students sitting next to each other.
That is the closest comparison, and Kuta Software is good software. It is also paid software you install on a computer. These worksheets run in a browser tab for free, with no account and nothing to install. Like Kuta, the conditional probability questions are generated when you ask for them rather than pulled from a fixed set of files, so two classes never get the same sheet, and the answer key comes with it.
Yes. There are two levels, and you can tick more than one for a sheet that mixes them, in which case the questions come out easiest first. The harder levels are not just larger numbers: they ask for something the easy ones do not.
You pick from 4: probability of a given b, from a two-way table, with the formula and conditional probability with p(a or b). Tick as many as you want and set how many of each, or let it spread them evenly.
Dividing by the whole group instead of the group the condition names. Given that they take Spanish, the denominator is the number of Spanish students, not the total.