Answer:
n=97
Step-by-step explanation:
1) Notation and definitions
population standard deviation known
Confidence=90% or 0.9
n sample size required (variable of interest)
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The sample mean have the following distribution
2) Calculation for the sample size required
In order to find the critical value we need to take in count that we are finding the interval for the mean with the population deviation known, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by and . And the critical value would be given by:
The margin of error for the sample mean interval is given by this formula:
(a)
And on this case we have that and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
And replacing into equation (b) the values from part a we got:
And rounded up we have that n=97
The number is 560.
The percentage is a ratio that can be expressed as a fraction of 100.
Let the required number be x.
Then, it follows that 1344 is 240% of x:
1344 = 240% of x
1344 = 240x/100
1344 = 12x/5
x = 1344×5/12
x = 560
Hence, the number is 560.
Learn more on percentages here:
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Answer:
49+2m
Step-by-step explanation:
49 is increased by twice a number m
Hope this helps!
2
4
8
16
Answer:
Cross Products Property of Proportions states that the product of the means is equal to the product of extremes.
i,e
Also, in the proportion the first (a) and the last terms(d) are called the extremes, whereas the second(b) and the third terms(c) are called the means.
Given the proportion:
First term = 1
Second term = 2
Third term = 4
Fourth term = 8
By definition;
The product of means =
The product of extremes =
Therefore, the product of both the means and the extremes is, 8
Answer:
JL = 7
Step-by-step explanation:
If JK = 4, KL = 3x, and JL = 7x, what is JL?
From the diagram given in tbe question,
JK + KL = JL
4 + 3x = 7x
Collect like terms
4 = 7x - 3x
4 = 4x
4x = 4
x = 4/4
x = 1
Since JL from the diagram = 7x
Hence:
7 × 1 = 7
JL = 7