Question bank/JEE Advanced/Mathematics

An engineer is required to visit a factory for exactly four days during the first 15 days of every month and it is mandatory that no two visits take place on consecutive days. Then what is the number of all possible ways in which such visits to the factory can be made by the engineer during 1-15 June 2021?

Source: JEEBench (IIT Delhi) / JEE Adv 2020 Paper 2