Find the distance CD rounded to the nearest tenth
1 answer:
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Answer:
9,765 cm
Step-by-step explanation:
We'll solve out the measurements for triangle ABC then it will be easy to figure out x
For triangle ABC, we have
Angle B = 90 degrees.
Angle A (CAB) = 38 degrees (the angle CAD is 19 and is said to be half of CAB, since the line AD is a bisector).
Angle C = 180 - 90 - 38 = 52 degrees.
To find the measurement of the BC line, which we label a, we know that
So, we can isolate the a to get:
Now we know the segment BC is 19.53 cm.
And we know that segments CD and DB are equal, since AD is a bisector, cutting the CAB angle in half.
So, CD is half of BC.... so 19.53 / 2 = 9.765 cm
Answer:
a) To determine the minimum sample size we need to use the formula shown in the picture 1.
E is the margin of error, which is the distance from the limits to the middle (the mean) of the confidence interval. This means that we have to divide the range of the interval by 2 to find this distance.
E = 0.5/2 = 0.25
Now we apply the formula
n = (1.645*0.80/0.25)^2 = 27.7 = 28
The minimum sample size would be 28.
b) To answer the question we are going to make a 90% confidence interval. The formula is:
(μ - E, μ + E)
μ is the mean which is 127. The formula for E is shown in the picture.
E = 0.80*1.645/√8 = 0.47
(126.5, 127.5)
This means that the true mean is going to be contained in this interval 90% of the time. This is why it doesn't seem possible that the population mean is exactly 128.
