10.1 Estimating a Population Mean

To assess the accuracy of a laboratory scale, a standard weight known to weigh 10 grams is weighed repeatedly. The scale readings are Normally distributed with unknown mean (this mean is 10 grams if the scale has no bias) In previous studies, the standard deviation of the scale readings has been about 0.0002 gram. How many measurements must be averaged to get a margin of error of 0.0001 with 98% confidence?

• At Least 5

• At Least 22

• At Least 16

• At Least 4.66

What does the T distribution depend on?

• The population mean

• The degrees of freedom

• The sample size

• The Z star value

Define the parameter of interest for this check your understanding problem.

• 
  

  μ=the true mean healing rate for newt skin wounds

• 
  

  x-bar= the true mean healing rate for newt skin wounds

• p=the true healing rate for newt skin wounds

  
  

What inference method will you use?

• 1-sample z-interval for means

• 1-sample t-interval for means

• 1-proportion z-interval for proportions

Construct a 95% confidence interval for μ. (Enter the data into L1 in your calculator, Go to T-Interval (#8) in the Tests column of the Stat menu, and use the Data in L1 to calculate the interval)

• (21.929, 29.404)

• 
  

  (21.527, 29.806)