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Fed [463]
3 years ago
10

One winter night the temperature fell 16 degrees between midnight and 5 A.M. By 9 A.M.the temperature had doubled from what it w

as at 5 A.M. By​ noon, it had risen another 12 degrees to 30 degrees. What was the temperature at​ midnight?
Mathematics
1 answer:
yarga [219]3 years ago
5 0
2(x - 16) + 12 = 30
2x - 32 + 12 = 30
2x - 20 = 30
2x = 30 + 20
2x = 50
x = 50/2
x = 25 <=== the temp was 25 at midnight


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In order to find the critical values we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical values would be given by:

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And on this case we have that ME =\pm 0.01 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

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And replacing into equation (b) the values from part a we got:

n=\frac{0.2(1-0.2)}{(\frac{0.01}{1.96})^2}=6146.56  

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