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

A sphere has a radius of 7 cm. What is its volume?

View Question

If a person can type 45 words per minute, how many words can they type in 2 hours?

View Question

If x² - 9x + 18 = 0, what are the roots of the equation?

View Question

If the sides of a triangle are 6 cm, 8 cm, and 10 cm, what is the area of the triangle?

View Question

What is the square root of 0.25?

View Question

A train 120 meters long is moving at a speed of 54 km/h. How long will it take to pass a pole?

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 HCF of 72 and 120?

View Question

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

View Question

The sum of the squares of two consecutive integers is 145. What are the integers?

View Question