The management team of a call center is making some reductions to staff. They must decide between two outbound salespeople and they plan to make their decision based on who has a higher probability of making sales. They know that in the sales business repeat calls to close a sale are common, so the management team will consider the total success rate of up to four calls. Bert has a record of closing on the first call 70% of the time, with the probability of a sale dropping 10% with each successive call. Riley has a record of closing on the first call 56% of the time, with the probability of a sale dropping 5% with each successive call.

1. Bert has what percent chance of closing a call within the first four calls?
2. Riley has what percent chance of closing a call within the first four calls?
3. The probability of a sale for Bert to make a sale on the fourth call to any given client is?
4. The probability of a sale for Riley to make a sale on the fourth call to any given client is?
5. Based on their results, whom should management let go and whom should they keep?

Be sure to reference at least one scholarly source to support your answer.