It is known that 80% of the customers at a DIY store own a discount card. Customers queuing at a checkout are asked if they own a discount card.

a. Find the probability that the first customer who owns a discount card is:

i. The third customer asked 

ii. Not one of the first four customers asked.

b. Given that 10% of the customers with discount cards forget to bring them to the store, find the probability that the first customer who owns a discount card and remembered to bring it to the store is the second customer asked.