The outlier 78, is removed from the data set show 23,23,25,27,34,34,35,41,45,78. how does this affect the range

The range will get smaller.

The old range was 
old range = max - min
old range = 78 - 23
old range = 55

If we remove 78 from the set, then the new range is 
new range = (new max) - min
new range = 45 - 23
new range = 22

So the range has gone from 55 to 22.