The probability that all marbles are yellow is
(7/20) (7/20) (7/20) = 343/8000
We are given
x = 2 and 3
u = 2.5
s = 0.5
Getting the z score
z = (2 - 2.5) / 0.5 and (3 - 2.5)/ 0.5
z = -1 and 1
The percentage is
1 - 0.1557 = 81.5%
34% = 0.34
120 * 0.34 = 40.8
Solution: it is 40.8
<span>A medical researcher wants to investigate the amount of time it takes for patients' headache pain to be relieved after taking a new prescription painkiller. She plans to use statistical methods to estimate the mean of the population of relief times. She believes that the population is normally distributed with a standard deviation of 18 minutes. How large a sample should she take to estimate the mean time to within 4 minutes with 97% confidence?
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n = [z*s/E]^2
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n = [2.17*18/4]^2 = 96 when rounded up
</span>
0.800 is already rounded to the nearest tenth
