asrigordonLv1

15 Oct 2022

Question 8

When using the CLT, it is very easy to end up with rounding errors depending on how you enter the standard deviation of the sampling distribution. Remember that the formula is:

 

 

 

Suppose you take a random sample of 7 values from a normally distributed population with mean 20 and standard deviation $6.2$.

 

a. Find and round to one decimal: ________

Now use the normalcdf (TI) or NormalDist.Cdf (ClassCalc) command to find the following, rounding each answer to 4 decimals.

 

b. Find using your rounded answer to part a: _________

 

c. Find by entering instead: ______

 

Even though the answers in parts b and c are close, on later problems the system might grade your answer as incorrect if you use a rounded value for $\sigma_x$ like you did in part b. So be sure to enter an "exact" value, as you did in part c, to avoid rounding errors.

 

You should follow the same process when using the invNorm (TI) or NormalDist.inverseCdf (ClassCalc) command.

 

d. Find the value of a (to 2 decimals) such that P ( < a) = 0.85. ______