Working backwards from a probability
Working backwards from a probability

Probability equation questions ask you to work backwards from a known probability to an unknown number of counters. A tree diagram like the one above helps you keep track of what changes after the first draw.
Step-by-step lessons on Edexcel IGCSE Maths Probability Equation Questions. Each one builds up to exam-style questions. Build confidence with the shared Foundation-tier content first, since roughly 40% of Higher-tier marks are targeted at the grades 4–5 boundary that both tiers have in common.