Topic Details (Notes format)

How to Solve Direct and Inverse Variation Problems

Subject: Mathematics

Book: Maths Mastery

Direct variation follows y = kx, where y changes proportionally with x (e.g., doubling x doubles y). Inverse variation follows y = k/x, implying that multiplying x by a factor divides y by the same factor. For instance, if y ∝ x, you might have y = 3x; doubling x from 2 to 4 changes y from 6 to 12. Conversely, if y ∝ 1/x, and x changes from 2 to 4, y becomes half. Variation problems are integral in physics (Ohm’s Law), chemistry (pressure-volume relationships), and everyday concepts like speed-time relationships. Mastering them helps you interpret how one quantity shifts in response to another.

Practice Questions

If a:b = 7:9 and b:c = 5:6, what is a:c?

View Question

If 2a + b = 10 and a - b = 4, what is the value of a?

View Question

A man rows downstream at 6 km/h and upstream at 4 km/h. What is the speed of the stream?

View Question

What is the sum of the first 50 positive integers?

View Question

What is the length of the diagonal of a square with a side length of 7 cm?

View Question

The sum of the reciprocals of two numbers is 1/4. If one number is 12, what is the other?

View Question

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

View Question

If the sum of the angles of a polygon is 1080°, how many sides does the polygon have?

View Question

If a:b = 5:7 and b:c = 6:11, what is a:c?

View Question

If sin(A) = 3/5 and cos(B) = 5/13, where A and B are acute angles, what is sin(A+B)?

View Question