For this case we have the following inequality:
We multiply both sides of the equation by -1.
By doing this, change the symbol of the inequality.
We have then:
From here, we clear the value of x.
We have then:
Answer:
The solution set is:
{x | x R, x < -12}
Answer:
A sample of 179 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 = 1.44.
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.
A previous study found that for an average family the variance is 1.69 gallon?
This means that 
If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?
A sample of n is needed, and n is found for M = 0.14. So
Rounding up
A sample of 179 is needed.
Answer and explanation:
A. What is the probability that more than half of the sample of 100 computers would need warranty service?
What is the probability that more than half of the sample of 100 computers would not need warranty service?
What is the probability that out of sample of 100 more than 20% would require warranty service?
B. If our sample of 100 computers of that brand and model reveals that 30 computers need warranty service, does this give a valid conclusion that all such computers in the population would require about 30% warranty service or less?
