Answer:
Minimum number of calls = 10
Step-by-step explanation:
Lets name the five people as A,B,C,D and E.
<u>On the night before ,each person talks to every other person atleast once that means A would talk to B,C,D and E atleast once.</u>
Lets start with A. He would talk to other 4 people which means there would be 4 phone calls made.
Now lets take B. He can talk to A,C,D and E. But A has already talked to C therefore to get minimum number of phone calls , B need not call A again. So he calls only C,D and E.
In case of C using similar logic he need to talk to only D and E.
For D , he talks to E alone.
E does not have to talk to anyone as he has already talked to everyone atleast once.
Total calls = 4 + 3 + 2 + 1
= 10
