Answer:
Step-by-step explanation:
It is assumed the question is about finding the minimum value as the given function has no maximum value, it is + ∞ as the coefficient of x² is positive
<u>The minimum/maximum value of a quadratic function is the vertex, which is at:</u>
<u>For the given function y = x² -10x + 31, the vertex is:</u>
<u>The value of y at this point is:</u>
<u>The point is </u>
Answer:
A sample size of 385 is needed.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
That is z with a pvalue of , so Z = 1.96.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
You feel that a reasonable estimate of the standard deviation is 10.0 hours.
This means that
What sample size is needed so that the expected margin of error of your estimate is not larger than one hour for 95% confidence?
A sample size of n is needed. n is found when M = 1. So
Rounding up:
A sample size of 385 is needed.