Past data shows that the time to complete a tax form is 10 m

Past data shows that the time to complete a tax form is 10 minutes with a standard deviation of 2. A new form is introduced, with the aim to reduce the amount of time. A sample of size 100 is taken and the sample average time is 9.8 minutes. what is the z-value?

Solution

to find the p value we need first Z value

Z = [9.8-10] / [2 / srqt(100) ]

Z= -1

using tables of Z distribution to find the probability or p value ( is the same thing)

P( z < -1 ) = 0.16