Plzz help mehjDutch hchch h

Answer:
Step-by-step explanation:
Given the data set of 15 where:
As per given we conclude
a) Possible set is:
b) Add number 20, the set will be:
The mean is different as we have now more numbers with different sum:
The median is different now and moves to the right as 20 added to the far right:
The mode stays same as still most used number is 5: