Question

The heights of a certain species of plant are normally distributed, with mean 20 cm and standard deviation 2cm. What is the probabilty that a plant chosen at random will be between 19 & 21 cm tall?

Answer 1

There is a 38.29% chance of the plant being 19 to 21 cm tall.
This is found using the Normal CDF function on a TI89 in the stats/list editor.
If use choose F5->Normal CDF->and then enter "Lower Value = 19", "Upper Value = 21", mean = "20" and S.D.="2" you will get this result. Otherwise you need to use a z-table.