IQ and Lead Exposure: Confidence Interval The data set IQLEAD (found in the lab description) lists full IQ scores for a random sample of subjects selected from a group with low lead levels in their...

2: Find the 95% confidence interval

a) Press STAT & scroll to TESTS & select “2-SampTInt...” (option 0 in TI83Plus) & press Enter (for a hypothesis test of a claim involving two populations

b) Enter the following:

• Inpt:  Stats (The statistics are given above)


• 
  x̄1= sample mean from the low lead level group
  


• Sx1 = sample standard deviation from the low lead level group
  


• n1 = sample size from the low lead level group
  


• 
  x̄2= sample mean from the high lead level group
  


• Sx2 = sample standard deviation from the high lead level group
  


• n2 = sample size from the high lead level group
  


• 
  Pooled:  Choose NO
  

c) Highlight “Calculate” and press ENTER & make note of the calculations as you will need them below.

Enter the values of confidence interval below here.  Round each value to two decimal places.

The 95% confidence interval = ( _, _)