X=one type that cost 9
y=one type that cost 8
total books=type1+type2
total books=13
x+y=13
the total cost=cost of each added together
cost of each=number of books times cost per book
total cost=108
9x+8y=108
we have
x+y=13
9x+8y=108
solve for x and y
multiply first equation by -8 and add to first equation
-8x-8y=-104
<u>9x+8y=108 +</u>
x+0y=4
x=4
subsitute
x+y=13
4+y=13
minus 4
y=9
4 of the $9
9 of the $8
thats how to solve
Step-by-step explanation: This simple confidence interval calculator uses a Z statistic and sample mean (M) to generate an interval estimate of a population mean (μ).
Note: You should only use this calculator if (a) your sample size is 30 or greater; and/or (b) you know the population standard deviation (σ), and use this instead of your sample's standard deviation (an unusual situation). If your data does not meet these requirements, consider using the t statistic to generate a confidence interval.
where:
M = sample mean
Z = Z statistic determined by confidence level
sM = standard error = √(s2/n)
As you can see, to perform this calculation you need to know your sample mean, the number of items in your sample, and your sample's standard deviation (or population's standard deviation if your sample size is smaller than 30). (If you need to calculate mean and standard deviation from a set of raw scores, you can do so using our descriptive statistics tools.)
Answer:
2a - b = 5
Step-by-step explanation:
4a - 2b = 10
take out the highest common factor of the left side
2(2a - b) = 10
divide both sides by two
2a - b = 10/2
2a - b = 5
A confidence interval is simply the range of estimates for an unknown parameter, which is defined as an interval with a lower bound and an upper bound.
<h3>
What is a confidence interval?</h3>
Your information is incomplete as the data is not given. Therefore, an overview of the confidence interval will be given.
A 90% confidence interval means that the researcher is 90% confident that the values of the results will simply fall between the upper and lower limits if the procedure is repeated again.
You can find a confidence level for data by simply taking half of the size of the confidence interval, then multiplying it by the square root of the sample size, and then dividing by the sample standard deviation.
Finally, look up the resulting Z or t score in a table in order to find the level.
Learn more about confidence interval on:
brainly.com/question/15712887
Find the value of the trigonometric function.