Answer:
The 99% confidence interval of the population standard deviation is 1.7047 < σ < 7.485
Step-by-step explanation:
Confidence interval of standard deviation is given as follows;
s =
Where:
= Sample mean
s = Sample standard deviation
n = Sample size = 7
χ = Chi squared value at the given confidence level
= ∑x/n = (62 + 58 + 58 + 56 + 60 +53 + 58)/7 = 57.857
The sample standard deviation s = = 2.854
The test statistic, derived through computation, = ±3.707
Which gives;
1.7047 < σ < 7.485
The 99% confidence interval of the population standard deviation = 1.7047 < σ < 7.485.
Using the normal distribution, it is found that 58.97% of students would be expected to score between 400 and 590.
<h3>Normal Probability Distribution</h3>
The z-score of a measure X of a normally distributed variable with mean and standard deviation is given by:
- The z-score measures how many standard deviations the measure is above or below the mean.
- Looking at the z-score table, the p-value associated with this z-score is found, which is the percentile of X.
The mean and the standard deviation are given, respectively, by:
The proportion of students between 400 and 590 is the <u>p-value of Z when X = 590 subtracted by the p-value of Z when X = 400</u>, hence:
X = 590:
Z = 0.76
Z = 0.76 has a p-value of 0.7764.
X = 400:
Z = -0.89
Z = -0.89 has a p-value of 0.1867.
0.7764 - 0.1867 = 0.5897 = 58.97%.
58.97% of students would be expected to score between 400 and 590.
More can be learned about the normal distribution at brainly.com/question/27643290
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You convert a decimal to a fraction by putting the digits to the right of the decimal point over "1" followed by the same number of zeros. (Most folks learn this in 3rd or 4th grade.)
0.66 = 66/100 . . . . . 2 decimals, so the denominator is 100
Then you reduce the fraction by canceling common factors. It helps to know your times tables and divisibility rules. (Or you can have your calculator do it.)
0.66 = 66/100 = 33/50
1.00 = 100/100 = 1
Answer: The answer is 1/2 1/4 and 1/9
Step-by-step explanation: I did it already and i got it right