TrueorFalse?

1. In a contingency table, if row percentages in one row are very different from those in another row, that indicates association.
2. If a parameter is computed from a data set, the data were obtained from a census.
3. If X and Y are random variables with standard deviations of 3 and 4 respectively, then it is always true that the standard deviation of X+Y is 5.