Question

The piston diameter of a certain hand pump is 0.4 inch. The manager determines that the diameters are normally distributed, with a mean of 0.4 inch and a standard deviation of 0.003 inch. After recalibrating the production machine, the manager randomly selects 21 pistons and determines that the standard deviation is 0.0021 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the 0.10 level of significance? What is the P-value?

Answer #1

The piston diameter of a certain hand pump is 0.4 inch. The
manager determines that the diameters are normally distributed,
with a mean of 0.4 inch and a standard deviation of 0.004 inch.
After recalibrating the production machine, the manager randomly
selects 28 pistons and determines that the standard deviation is
0.0035 inch. Is there significant evidence for the manager to
conclude that the standard deviation has decreased at the alpha
equals 0.05 level of significance?

the piston diameter of a certain hand pump is 0.7
inch. the manager determines that the diameters are normally
distributed, with a mean od 0.7 inch and a standard deviation of
0.003. after recalibrating the production machine the manager
randomly selects 23 pistons and determines that the standard
deviation is 0.0021inch.is there significant evidence for the
manager to conclude that the standard deviation has decreased at
the Alpha 0.10 level of significance

The piston diameter of a certain hand pump is 0.7 inch. The
manager determines that the diameters are normally distributed,
with a mean of 0.7 inch and a standard deviation of 0.003 inch.
After recalibrating the production machine, the manager randomly
selects 23 pistons and determines that the standard deviation is
0.0021 inch. Is there significant evidence for the manager to
conclude that the standard deviation has decreased at the alpha
equals 0.10 level of significance? Use technology to determine...

Suppose a mutual fund qualifies as having moderate risk if the
standard deviation of its monthly rate of return is less than 5%.
A mutual-fund rating agency randomly selects 21 months and
determines the rate of return for a certain fund. The standard
deviation of the rate of return is computed to be 3.42%. Is there
sufficient evidence to conclude that the fund has moderate risk at
the alpha equals 0.01 level of significance? A normal probability
plot indicates that...

The diameters of a random sample of 20 products made by a
certain machine during one month showed a mean of 0.93 inch and a
sample standard deviation of 0.05 inch. Assume the population is
normally distributed, find a 95% confidence intervals for the mean
diameter of all the products.
Select one:
a. 0.9066 to 0.9534 inch
b. 0.9081 to 0.9519 inch
c. 0.9248 to 0.9352 inch
d. 0.9107 to 0.9493 inch
“Is live lecture over Zoom an effective way...

Suppose a mutual fund qualifies as having moderate risk if the
standard deviation of its monthly rate of return is less than 5?%.
A? mutual-fund rating agency randomly selects 21 months and
determines the rate of return for a certain fund. The standard
deviation of the rate of return is computed to be 3.28?%. Is there
sufficient evidence to conclude that the fund has moderate risk at
the alpha equals 0.05 level of? significance? A normal probability
plot indicates that...

Question 5: Assume that you make candy bars; the advertised
weight of the candy bar is 4.0 ounces with a standard deviation
(sigma) of 2.35 oz. however your production manager thinks that
this is not true; he thinks the candy bars are over-weight, they
weigh more than 4.0 oz. To test his claim, you
decided to randomly select a sample of 126 candy bars, the average
weight (x-bar) is 4.5 oz. At an alpha (a) of 0.01 what do you...

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