At a bank, a teller takes 5 minutes to start a mortgage process for a client of a bank and 15 minutes to do that for a n

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At a bank, a teller takes 5 minutes to start a mortgage process
for a client of a bank and 15 minutes to do that for a non-client.
Client's mortgage is then finalized and it additionally takes 0.5
hours to finalize the entire process. A particular branch of a bank
processes 4 customers per day (assuming 8 hours in a day). If 10
customers per hour arrive to this particular branch, what fraction
of these customers are clients of the bank? (Multiple choices
may be correct)
10%
cannot determine exactly
90%
80%
30%
50%
70%
60%
100%