The masses of a specific breed of adult dog are normally distributed with a mean of 24 kg24\text{ kg}24 kg and a standard deviation of 5 kg5\text{ kg}5 kg.
Find the probability that a randomly selected dog from this breed has a mass greater than 31.5 kg31.5\text{ kg}31.5 kg.
Any dog of this breed with a mass greater than 31.5 kg31.5\text{ kg}31.5 kg is classified as "heavy".
A dog of this breed is chosen at random. Given that it is classified as heavy,
find the probability that it has a mass greater than 36 kg36\text{ kg}36 kg.
Among the heavy dogs, exactly 25%25\%25% have a mass greater than m kgm\text{ kg}m kg.
Find the value of mmm.
164 exam-style questions on WJEC A Level Maths 4.1 Probability (A-level only), covering 4.1.1 Probability (A-level only), 4.1.2 Probability (A-level only), and 4.1.3 Probability (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.