Method: Exponential Problems

Part of Compound Interest · Section 3 of 6

Deep DiveUnit: Ratio & ProportionGCSE

1 Identify: growth (+r) or decay (-r)?

2 Find the multiplier: (1+r) or (1-r)

3 Write formula with starting value and time periods

4 Calculate using power button on calculator

This deep dive covers Method: Exponential Problems within Compound Interest for GCSE Mathematics. Revise Compound Interest in Ratio & Proportion for GCSE Mathematics with 12 exam-style questions and 4 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 3 of 6 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Practice questions for Compound Interest

Which formula correctly calculates the amount A after compound interest at rate r% per year for n years on principal P?

A. A = P × (1 + r/100) × n
B. A = P × (1 + r/100)^n
C. A = P + P × r/100 × n
D. A = P × r^n / 100

1 markfoundation

£2,000 is invested for 4 years. - Account A pays 5% simple interest per year. - Account B pays 4.5% compound interest per year. Which account gives more money after 4 years? Show all working.

3 marksstandard

Quick recall flashcards

Growth vs Decay

Growth: multiply by (1+r). Decay: multiply by (1-r). The multiplier is raised to the power of n (time periods).

Exponential Decay

N = N₀ × (1 - r)^t for decay rate r

Key Facts

Worked Example 1: Population Growth

12 questions on Compound Interest: practise free

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