The solution should be done using Excel:

XYZ Corporation assembles parts for a local manufacturing firm. They have 200 experienced workers on assembly line. These workers typically assemble parts where only 7% parts have a chance to be defective. Recently the company received large orders and has to hire another 100 people. They decided to form two groups. In the first group they placed 120 experienced workers (7% chance of defective parts) who would do half of the work (50%). The second group further divided into two subgroups. First subgroup has 50 experienced workers and 60 workers with some experience. This subgroup can assemble parts where only 20% parts have a chance to be defective. This group is going to assemble 30% of the parts. The second subgroup has only 30 experienced workers and 40 inexperienced workers. This subgroup is going to assemble the remaining 20% of the parts that have a 30% chance to be defective. What is the probability that 7 out of 30 parts tested and found to be defective, are assembled by first group (all experienced workers). Please submit your spread sheet with values as well as with formulae (only first couple pages showing the final result)