Answer:
Step-by-step explanation:
We want to determine a 98% confidence interval to estimate the true mean shear strength of anchor bolts.
Number of sample, n = 78
Mean, u = 4.25
Standard deviation, s = 1.3
For a confidence level of 98%, the corresponding z value is 2.33.
We will apply the formula
Confidence interval
= mean ± z × standard deviation/√n
It becomes
4.25 ± 2.33 × 1.3/√78
= 4.25 ± 2.33 × 0.147
= 4.25 ± 0.34
The lower end of the confidence interval is 4.25 - 0.34 = 3.91
The upper end of the confidence interval is 4.25 + 0.34 = 4.59
b) the confidence interval would still be valid because the number of samples is large(> 30)
The normal distribution is also known as the Gaussian distribution. The correct option is D, while the z-score is -2.29.
<h3>What is Normal Distribution?</h3>
The normal distribution, also known as the Gaussian distribution, is a symmetric probability distribution about the mean, indicating that data near the mean occur more frequently than data distant from the mean. The normal distribution will show as a bell curve on a graph.
Since the normal distribution is symmetrical about the mean. Therefore, 0.89 area from the left will be equal to 0.11 area from the right. Therefore, the correct option is D, while the z-score is -2.29.
Learn more about Normal Distribution:
brainly.com/question/15103234
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Answer:
mode = the most
mean =average of the numbers: a calculated "central" value of a set of numbers. ... add up all the numbers, • then divide by how many numbers there are.
median=The middle number; found by ordering all data points and picking out the one in the middle (or if there are two middle numbers, taking the mean of those two numbers).
<h3>
Mark</h3>
Now we arrange all Mark's test scores first (arrange in a sequence), so it will become :
71, 74, 76, 82, 83, 94, 94
mode = 94
mean = (71 +74+76+82+83+94+94) over 7
= 574 over 7
= 82
median = 82
<h3>
Irina</h3>
Now we arrange all Irina's test scores first (arrange in a sequence too) , so it will become :
79, 79, 82, 83, 89, 95, 95
mode (there are 2 modes in Irina test) which is 79 and 95 because both of them appears twice.
mean = (79+79+82+83+89+95+95) over 7
= 602 over 7
= 86
median = 83
<h3>
HOPE IT HELP</h3>
