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2 answers:
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Answer:
Step-by-step explanation:
Directions
- Draw a circle
- Dear a chord with a length of 24 inside the circle. You just have to label it as 24
- Draw a radius that is perpendicular and a bisector through the chord
- Draw a radius that is from the center of the circle to one end of the chord.
- Label where the perpendicular radius to the chord intersect. Call it E.
- You should get something that looks like the diagram below. The only thing you have to do is put in the point E which is the midpoint of CB.
Givens
AC = 13 inches Given
CB = 24 inches Given
CE = 12 inches Construction and property of a midpoint.
So what we have now is a right triangle (ACE) with the right angle at E.
What we seek is AE
Formula
AC^2 = CE^2 + AE^2
13^2 = 12^2 + AE^2
169 = 144 + AE^2 Subtract 144 from both sides.
169 - 144 = 144-144 + AE^2 Combine
25 = AE^2 Take the square root of both sides
√25 = √AE^2
5 = AE
Answer
The 24 inch chord is 5 inches from the center of the circle.
Answer:
78.81%
Step-by-step explanation:
We are given;
Population mean; μ = 149
Sample mean; x¯ = 147.8
Sample size; n = 88
standard deviation; σ = 14
Z-score is;
z = (x¯ - μ)/(σ/√n)
Plugging in the relevant values;
z = (147.8 - 149)/(14/√88)
z = -0.804
From z-distribution table attached, we have; p = 0.21186
P(X > 147.8) = 1 - 0.21186 = 0.78814
In percentage gives; p = 78.81%
I have an expression
floating around in my head; let's see if it makes sense.
The variance of binary valued random variable b that comes up 1 with probability p (so has mean p) is
That's for an individual sample. For the observed average we divide by n, and for the standard deviation we take the square root:
Plugging in the numbers,
One standard deviation of the average is almost 2% so a 27% outcome was 3/1.9 = 1.6 standard deviations from the mean, corresponding to a two sided probability of a bit bigger than 10% of happening by chance.
So this is borderline suspect; most surveys will include a two sigma margin of error, say plus or minus 4 percent here, and the results were within those bounds.