Simplify the following expression: -3(4x-2) -2x
2 answers:
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Answer:
a) The standard deviation of x must be 0.25 inches.
b) We need a sample of 125 to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a).
Step-by-step explanation:
The 68-95-99.7 states that:
68% percent of the measures of a normally distributed sample are within 1 standard deviation of the mean.
95% percent of the measures of a normally distributed sample are within 2 standard deviations of the mean.
99.7% percent of the measures of a normally distributed sample are within 3 standard deviations of the mean.
The standard deviation of the population is 2.8. This means that .
(a) What standard deviation must x⎯⎯⎯ have so that 95% of all samples give an x⎯⎯⎯ within one-half inch of μ?
We want to have a sample in which 2 standard deviations are within 0.5 inches of the mean.
So, the standard deviation of the sample must be:
The standard deviation of x must be 0.25 inches.
(b) How large an SRS do you need to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a)?
We have that the standard deviation of a sample of length n is given by the following formula:
.
We want and we have
. So
We need a sample of 125 to reduce the standard deviation of x⎯⎯⎯ to the value you found in part(a).
We are given the functions 
and 
.
let's consider some pairs in the graph of both functions.
in we have (-2, 4), (2, 4), (3, 9), (-5, 25)
in
we have (-2, -4), (2, -4), (3, -9), (-5, -25)
so for the same values of x, we have y's of equal value, but different sign.
This means that the functions are the reflections of each other with respect to the x-axis.
Answer: C <span>reflection over the x-axis</span>
let's consider some pairs in the graph of both functions.
in
in
so for the same values of x, we have y's of equal value, but different sign.
This means that the functions are the reflections of each other with respect to the x-axis.
Answer: C <span>reflection over the x-axis</span>