5. The average monthly rainfall for city A is 91mm with a standard deviation of 3.58 and for a city, B is 73mm with a standard deviation of 2.87. Last month, city A registered a rainfall of 45mm and in city B 39mm. Taking last month’s scores, how much closer or further from the mean would City A’s rainfall be compared to City B if City A had the same average distribution as that of city B?

- -21.6
- 2.9
- -9.75
- -2.1

The correct answer is

D. For City B last month’s rainfall we have: = –11.8

For City A last month’s rainfall with City B’s distribution:

The difference between z-scores: -11.8 – (-9.7) = -2.1. City A is 2.1 units closer to the mean compared to city B.