A family purchased a new ski boat for $18,500. The loan agency required a 10% down payment and financed the balance for 36 month
1 answer:
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Answer:
The 99% confidence interval would be given (11.448;14.152).
Step-by-step explanation:
1) Important concepts and notation
A confidence interval for a mean "gives us a range of plausible values for the population mean. If a confidence interval does not include a particular value, we can say that it is not likely that the particular value is the true population mean"
represent the sample deviation
represent the sample mean
n =1003 is the sample size selected
Confidence =99% or 0.99
represent the significance level.
2) Solution to the problem
The confidence interval for the mean would be given by this formula
We can use a z quantile instead of t since the sample size is large enough.
For the 99% confidence interval the value of and
, with that value we can find the quantile required for the interval in the normal standard distribution.
And replacing into the confidence interval formula we got:
And the 99% confidence interval would be given (11.448;14.152).
We are confident that about 11 to 14 are the number of books that the people had read on the last year on average, at 1% of significance.
Answer:
The correct answer is 15 cm.
Step-by-step explanation:
Let the width of the required poster be a cm.
We need to have a 6 cm margin at the top and a 4 cm margin at the bottom. Thus total margin combining top and bottom is 10 cm.
Similarly total margin combining both the sides is (4+4=) 8 cm.
So the required printing area of the poster is given by {( a-10 ) × ( a - 8) }
This area is equal to 125 as per as the given problem.
∴ (a - 10) × (a - 8) = 125
⇒ - 18 a +80 -125 =0
⇒ - 18 a -45 = 0
⇒ (a-15) (a-3) = 0
By law of trichotomy the possible values of a are 15 and 3.
But a=3 is absurd as a 4.
Thus the required answer is 15 cm.