To solve for the confidence interval for the true average
percentage elongation, we use the z statistic. The formula for confidence
interval is given as:
Confidence interval = x ± z σ / sqrt (n)
where,
x = the sample mean = 8.63
σ = sample standard deviation = 0.79
n = number of samples = 56
From the standard distribution tables, the value of z at
95% confidence interval is:
z = 1.96
Therefore substituting the known values into the
equation:
Confidence interval = 8.63 ± (1.96) (0.79) / sqrt (56)
Confidence interval = 8.63 ± 0.207
Confidence interval = 8.42, 8.84
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Answer:
Part A: chosen method is by factoring
Part B: First rewrite the equation by writing -24 as a difference so you get x² -9x - 15x + 135 = 0. Then factor out the x and the -15 from the equation so you get x(x-9) - 15(x-9) = 0. Then factor out x-9 from the equation so you have (x-9)(x-15) = 0. Finally, set each expression to 0: x-9=0 and x-15=0 and then solve: x=9 and x=15
Part C: x=9, x=15
Answer:
108
Step-by-step explanation:
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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Answer:
Step-by-step explanation:
The first one.