Download 1. Suppose you are working with a data set that is normally

1. Suppose you are working with a data set that is normally distributed with a mean of 400 and a
standard deviation of 20. Determine the value of x such that only 1% of the values are greater than
x.
353.4
446.6
405
400.039
Using the NORMINV function in Excel, we can the value. NORMINV(0.99,Mean,Stdev) i.e.
NORMINV(0.99,400,20) = 446.6
2. When the rod shearing process at Stockton Steel is "in control" it produces rods with a mean
length of 120 inches. Periodically, quality control inspectors select a random sample of 36 rods. If
the mean length of sampled rods is too long or too short, the shearing process is shut down. The
null hypothesis is _________.
n = 36
μ = 120
μ ≠120
n ≠36
Since we want to test whether the rods are 120 inches in length or not. The null hypothesis is μ =
120, since we cannot have a NOT EQUAL to sign in the null hypothesis.