The heights of a specific species of plant are normally distributed. 20% of the plants are shorter than 15 cm. 10% of the plants are taller than 25 cm.
Find the mean and standard deviation of the heights of the plants.
48 exam-style questions on Edexcel A Level Maths 3.5 Finding the mean and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.