Chapter 18 Sampling Distribution
Key Concepts
Example 1 Suppose that about 13% of the population is left handed. A 200 seat school auditorium has been built with 15 lefty seats. In a class of 90 students what is the probability that there will not be enough seats for the left handed students?
Plan We want the probability of finding more that 16.7% left handed students out of a sample size of 90 students if the proportion of lefties is 13%.
Always check conditions Randomization Condition: 10% condition: Success/ Failure np>10 nq > 10
State the parameter and the sampling distribution model p= The conditions are satisfied N( mean ( use population proportion), SD) N(.13,.035)
Draw it
Find the z-score z= P( p >.167) =
Example 2 Information on a packet of seeds claims that the germination rate is 92%. What is the probability that more than 95% of the 160 seeds in the packet will germinate?
Plan
Conditions
State the parameter and the sampling distribution model p= The conditions are satisfied N( mean ( use population proportion), SD) N( )
Plot it
z score