Answer:
400 megabytes of data used will make the cost from either company equal.
Step-by-step explanation:
Given that:
Per month charges of Company A = $80
Charges of 100 MB = $5 = 
Let,
x be the number of MBs consumed.
y be the total charges.
y = 0.05x+80
Per month charges of Company B = $60
Charges of 100 MB = $10 = $0.1 per MB
y = 0.1x+60
For equal charges;
0.05x+80 = 0.1x + 60
80-60 = 0.1x-0.05x
20 = 0.05x

Hence,
400 megabytes of data used will make the cost from either company equal.
The value of z* should be used to construct a 97 confidence interval of a population mean is 2.17.
<h3>What is confidence interval?</h3>
A degree of uncertainty and certainty in a sample process is measured by confidence intervals. They can choose from a variety of probability limitations, the most frequent becoming a 95% or 99% confidence level.
Some characteristics of confidence interval are-
- Statistical tools, such as the t-test, are used to compute confidence intervals.
- Confidence intervals are used by statisticians to quantify uncertainty in such a sample variable.
- A researcher, for example, may randomly select multiple samples drawn from the same population and compute a confidence interval for every sample to determine how well it might represent the real value of a population variable.
- The generated datasets are all unique; some intervals contain the genuine population parameter while others do not.
Now, according to the question;
The confidence level is given 97%.
Thus, the crucial value of z for a 97% confidence interval is 2.17, as determined by a z score table, which is as follows:

Therefore the obtained probability for the z-score of 2.17 is 0.97.
To know more about the confidence interval, here
brainly.com/question/15712887
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Answer:
A
Step-by-step explanation:
Answer:
1
2
− 1
9
8
Step-by-step explanation: