Answer this question, PLEASE A factory has 3 workshops, the output rate is 20%, 30%, 50%. The percentage of first-line products of workshops is: 90%, 85%, 80%.
a) randomly obtaining a factory product. probability to be a type one product.
b) get a refund 5 times at a time, one product at a time. Calculate the probability to have 3 times to get a first-type product.