:5. Solution. All the numbers on the new list are unchanged,
except for 15, which has been replaced by the (much) bigger
number 105. So the average of the new list is bigger than the
average of the old one.
The median of the old list is less than 15, so the 50% of
the numbers on it which are greater than or equal to the median
include the number 15. When the 15 is replaced by 150, it is
still true that 50% of the numbers on the resulting list are
greater than or equal to the (old) median. This implies that the
original median is the also the median of the new list. So A is
false and B is true.