If a salesperson has 7 customers in denver and 13 customers in reno then there are 20 different ways in which he can make calls.
Given that the salesperson has 7 customers in denver and 13 customers in reno.
We are required to find the number of ways in which he can make use of telephone.
Number of customers in denver=7
Number of customers in reno=13
Total customers=20
Since he can talk to one customer at one time and he can either choose customer from denver or reno, the number of ways by using combinations will be [tex]7C_{1}[/tex]+[tex]13C_{1}[/tex]
=7+13
=20 ways.
Hence if a salesperson has 7 customers in denver and 13 customers in reno then there are 20 different ways in which he can make calls.
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