Coding Grandmaster · project 21 of 46 · premium, free for now

Given that…

For the chosen club print how many students are in it, how many passed, and P(passed | club) as a percentage with one decimal place. Then print P(passed) for all students.

Learn

Conditional probability P(A | B) means the chance of A once you know B happened. You shrink the world to just the B cases, then count how many of those are also A. It is the heart of reasoning from evidence. Here a school keeps a list of pairs (club, passed) and asks: given the club, how likely was a pass?

Your task

For the chosen club print how many students are in it, how many passed, and P(passed | club) as a percentage with one decimal place. Then print P(passed) for all students.

Stretch challenge

Which club has the best pass rate, and is that the same as having the most passes?

← The OR rule Bayes and the medical test →

Python

Press Run to see what your program prints.

Keep going in Coding Grandmaster

Counting outcomes

Write ways(target), the number of dice pairs that add up to target, and as_fraction(top, bottom) that returns text like 1/6 in lowest terms. Print the chance of a total of 7.

Start →20

The OR rule

Build the 52-card deck as (rank, suit) pairs, then count the cards that are the chosen suit, the chosen rank, both, and either. Print the four counts and the chance of either as a fraction in lowest terms.

Start →22

Bayes and the medical test

Write posterior(prior, sensitivity, specificity) returning P(sick | positive) rounded to 4 decimal places. Print it for prior 0.01, sensitivity 0.9, specificity 0.9.

Start →23

The binomial distribution

Write binomial(n, k, p) and use it to print the chance of exactly 3 heads in 5 fair flips, the chance of at least 4 heads, and the total of all the chances (rounded to 6 places).

Start →24

How computers fake randomness

Write next_value(seed) with that formula, and roll(seed) = 1 + seed % 6. Starting from the given seed, roll 600 times (feeding each result back in) and print how many times each face 1 to 6 came up.

Start →

Practise the idea

📊 Play Data Detective

Use mean, median and mode to describe a set of data and compare what each tells you.

Play now

FAQ

Given that…: common questions

I am stuck. What can I do?

Press Hint for a nudge, read the message next to each goal, and compare your code with the lesson text. If you still need it, Show answer reveals a model solution. Try to type it yourself rather than copy it.

Does my work get saved?

Your ticks and XP are saved in this browser, and in your account if you log in. The code you type is not stored on a server.

Start a conversation

Enjoying coding? Meet a teacher.

Tell us the learner's age, country and what they would like to build, and we will suggest a class. A parent or guardian can make the enquiry.

Tell us the learner’s age or grade and goals
We’ll suggest a suitable class or learning path
We’ll confirm format, timing and fees with a parent or guardian

Play it, don't just read it

Write some code right now

Free games that need no sign-up. Pick one and play for five minutes.

All free games →

Pick a game

Today's maths challengeFive questions · the same for everyone today · keep your streak goingPlay