A botanical research study finds that 45% of seeds from a specific hybrid perennial germinate within the first 10 days of being sown. The seeds are packaged in sachets of 20 for commercial sale. A sachet is selected at random.
Determine the probability that the sachet contains exactly 9 seeds that germinate within 10 days.
Determine the probability that there are at least 13 seeds in the sachet that germinate within 10 days.
Using a suitable approximation, find the probability that in a bulk tray of 200 seeds, between 80 and 105 seeds (inclusive) germinate within 10 days.
67 exam-style questions on OCR A Level Maths 2.4.4 Mean and variance of the binomial (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.