Topic Details (Notes format)

How to Calculate Combinations (Unordered Selections)

Subject: Mathematics

Book: Maths Mastery

Combinations focus on ways to choose k items out of n without regard to order, calculated as C(n, k) = n! / [k!(n–k)!]. For instance, to find the number of ways to select 2 fruits from {Apple, Banana, Cherry}, you have 3 choices: AB, AC, BC, which is C(3, 2) = 3. Combinations appear in scenarios like forming committees, picking lottery numbers, or combining flavors in recipes. Understanding the difference between permutations and combinations clarifies everything from business inventory groupings to advanced probability, ensuring a robust combinatorial foundation.

Practice Questions

If a number is divisible by 9, it is also divisible by which of the following?

View Question

A rectangle has an area of 48 cm² and a length of 8 cm. What is its width?

View Question

What is the greatest common divisor (GCD) of 36 and 48?

View Question

The ratio of two numbers is 3:5, and their sum is 64. What are the numbers?

View Question

If a+b = 10 and ab = 21, what is the value of a^3 + b^3?

View Question

If a cylinder has a radius of 7 cm and height of 10 cm, what is its volume?

View Question

What is the 7th term of the arithmetic progression 3, 6, 9, 12,...?

View Question

If a square has a perimeter of 64 cm, what is its area?

View Question

If a + b = 10 and ab = 21, what is the value of a^2 + b^2?

View Question

How many diagonals does a pentagon have?

View Question