A botanical garden offers a "rare bloom" seed in 15% of its wildflower packets. No packet contains more than one rare bloom seed. Packets are sold in wholesale bundles of 12.
(i) Suggest a suitable distribution to model the number of rare bloom seeds, SSS, found in a single bundle. (ii) State one necessary assumption for this model to be valid.
Calculate the probability that out of 3 randomly selected bundles, exactly 1 bundle contains exactly 2 rare bloom seeds.
Determine the probability that a randomly selected bundle contains at least 3 rare bloom seeds.
A regional distributor buys 120 bundles for a seasonal sale.
Using a normal approximation, find the probability that fewer than 25 of these bundles contain at least 3 rare bloom seeds.
324 exam-style questions on WJEC A Level Maths 4.2 Statistical distributions (A-level only), covering 4.2.1 Statistical distributions (A-level only), 4.2.2 Statistical distributions (A-level only), and 4.2.3 Statistical distributions (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.