Agroup of 20 students are being asked to report the number of pets they keep in their house the results are 0,0,0,0,0,1,1,1,1,1,1,1,1,2,2,3,4,4 ,4,21

mean is 2.4
standard deviation is 4.47
quartile 1 is 0.5
median is 1
quartile 3 is 2.5

after being told that they should not count any fish in the report, the value of 3 becomes a 2 and the value of 21 becomes 1. would these changes affect the median, mean, standard deviation or inter quartile range ? if so would each measure decrease or increase from their original values?