A potential buyer of the breed of snake known as a rattlesnake wishes to find the average weight and length of a full-grown rept
2 answers:
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Answer:
The decision rule for rejecting the null hypothesis is
Step-by-step explanation:
A manufacturer of potato chips would like to know whether its bag filling machine works correctly at the 410 gram setting. It is believed that the machine is underfilling the bags.
At the null hypothesis, we test if the mean weight of the bag is the desired value of 410, that is:
At the alternate hypothesis, we test if the bag is underfilled, that is, the mean weight is below the desired value, so:
Type of test:
As we test if the mean is less than a value, we have a left-tailed test.
We have the standard deviation for the sample, which means that the t-distribution is used.
We have 22 - 1 = 21 degrees of freedom, with a level of significance of 0.05.
Using a calculator, the critical value is
Determine the decision rule for rejecting the null hypothesis.
We reject the null hypothesis if the test statistic is less than the critical value, so the decision rule for rejecting the null hypothesis is
Answer:
A sample size of 554 is needed.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
That is z with a pvalue of , so Z = 1.96.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
Standard deviation is known to be $12,000
This means that
What sample size do you need to have a margin of error equal to $1000, with 95% confidence?
This is n for which M = 1000. So
Dividing both sides by 1000:
Rounding up:
A sample size of 554 is needed.