Answer:
The 95% confidence interval estimate of the population mean life of the new light-bulb is (469.21 hours, 510.79 hours).
This confidence level means that we are 95% sure that the true population mean life of the new light bulb is in this interval.
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 
.
So it is z with a pvalue of 
, so 
Now we find M as such:
In which 
is the standard deviation of the population and n is the length of the sample. So:
The lower end of the interval is the mean subtracted by M. So it is 490 - 20.79 = 469.21 hours.
The upper end of the interval is the mean added to M. So it is 490 + 20.79 = 510.79 hours.
The 95% confidence interval estimate of the population mean life of the new light-bulb is (469.21 hours, 510.79 hours).
This confidence level means that we are 95% sure that the true population mean life of the new light bulb is in this interval.
Answer:
Step-by-step explanation:
32 students in 1 row
16 students in 2 rows
8 students in 4 rows
4 students in 8 rows
2 students in 16 rows
Answer:
1/12
Step-by-step explanation:
You are close but 1/27 includes people who did not study but still passed. If you want a singular value you should look at the value for the for only the people who studied even if they passed.
Answer:
a = 5 and b = 12
Step-by-step explanation:
<u>Step 1: Find angle B</u>
<em>Angle C = 90°</em>
<em>Angle A = 22.6°</em>
<em>Angle B = B</em>
<em>All angles in a triangle are equal to 180°.</em>
Angle A + Angle B + Angle C = 180°
22.6 + 90 + B = 180°
B = 180 - 112.6
B = 67.4°
<u>Step 2: Find the value of side AC 'b'</u>
<em>Hypotenuse = 13</em>
<em>Adjacent = b</em>
<em>Angle A = 22.6°</em>
Cos (Angle) = Adjacent/Hypotenuse
Cos (22.6) = b/13
b = 12
<u>Step 3: Find the value of side CB 'a'</u>
<em>Hypotenuse = 13</em>
<em>Opposite = a</em>
<em>Angle A = 22.6°</em>
Sin (angle) = Opposite/Hypotenuse
Sin (22.6°) = a/13
a = 4.99 rounded off to 5
Therefore, the value of a=5 and b=12.
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