Answer: C) 133
Step-by-step explanation:
The formula to find the sample size is given by :-
, where z* = Critical z-value
= Population standard deviation for prior study.
E= Margin of error.
As per given , we have
E= 5
The critical z-value for 90% confidence level is 1.645.
Substitute al;l the value sin the above formula , we get
Hence, the minimum sample size needed is 133.
Thus , the correct answer is : C) 133
Answer:
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Reason:
Plot the points (0,0) and (r,s). You can place (r,s) anywhere you want.
Connect the two points mentioned and form a right triangle such that the segment from (0,0) to (r,s) is the hypotenuse of said right triangle.
The horizontal leg has a length of r-0 = r units, while the vertical leg will be 's' units.
Check out the diagram below.
We then apply the pythagorean theorem to say where h is the hypotenuse. Solving for h gets us
. We only focus on the positive square root since a negative hypotenuse makes no sense.
Since we made the hypotenuse the segment with endpoints (r,s) and (0,0), this means the hypotenuse length and the distance are the same thing.
Therefore, the distance from (r,s) to (0,0) is
As an alternative, you can use the distance formula to get the same answer. The distance formula is effectively the pythagorean theorem phrased a different way.
