Geometry closes with probability, and conditional probability here is read from two-way tables and short word problems or worked with the rule P(A and B) = P(A) × P(B | A). Treat the given condition as a smaller group: that group becomes the whole you divide by.
Also taught in Algebra 2 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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A survey of 19 students found that 11 bring lunch from home and, of those, 7 also buy a drink at school. Find the probability that a student buys a drink at school given that they bring lunch from home.
There are 33 households in a study. Of them, 17 have a dog, 29 have a cat and 15 have both. Find the probability that a household has a dog given that it has a cat.
In a group of 19 travelers, 9 check a bag and, of those, 7 also bring a laptop. Find the probability that a traveler brings a laptop given that they check a bag.
Of the 33 gardeners asked, 10 grow tomatoes but do not grow peppers, 10 grow peppers but do not grow tomatoes, and 10 grow both. Find the probability that a gardener grows tomatoes given that they grow peppers.
There are 18 students in a study. Of them, 9 take Spanish and, of those, 2 also take art. Find the probability that a student takes art given that they take Spanish.
In a group of 36 employees, 4 drive to work but do not work from home some days, 6 work from home some days but do not drive to work, and 13 do both. Find the probability that an employee drives to work given that they work from home some days.
Of the 15 readers asked, 5 read mysteries and, of those, 3 also read science fiction. Find the probability that a reader reads science fiction given that they read mysteries.
Find a conditional probability from a two-way table
A survey of 19 students found that 11 bring lunch from home and, of those, 7 also buy a drink at school. Find the probability that a student buys a drink at school given that they bring lunch from home.117
There are 33 households in a study. Of them, 17 have a dog, 29 have a cat and 15 have both. Find the probability that a household has a dog given that it has a cat.2915
In a group of 19 travelers, 9 check a bag and, of those, 7 also bring a laptop. Find the probability that a traveler brings a laptop given that they check a bag.97
Of the 33 gardeners asked, 10 grow tomatoes but do not grow peppers, 10 grow peppers but do not grow tomatoes, and 10 grow both. Find the probability that a gardener grows tomatoes given that they grow peppers.21
There are 18 students in a study. Of them, 9 take Spanish and, of those, 2 also take art. Find the probability that a student takes art given that they take Spanish.92
In a group of 36 employees, 4 drive to work but do not work from home some days, 6 work from home some days but do not drive to work, and 13 do both. Find the probability that an employee drives to work given that they work from home some days.1913
Of the 15 readers asked, 5 read mysteries and, of those, 3 also read science fiction. Find the probability that a reader reads science fiction given that they read mysteries.53
Find a conditional probability from a two-way table
The condition is Grade 10, so use only that column: 18 + 10 = 28.
18 of those walk.
18/28 simplifies to 9/14.
The answer is 149.
Where students go wrong
Reading P(A | B) as P(B | A). P(walk | grade 10) divides by the grade 10 column total, while P(grade 10 | walk) divides by the walk row total, and the two are usually different.
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.
Geometry is usually taken around 9th or 10th 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.