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raketka [301]
3 years ago
5

A nurse at a local hospital is interested in estimating the birth weight of infants. how large a sample must she select if she d

esires to be 98% confident that the tue mean is within 3 ounces of sample mean. the standard deviation of birth weights is known to be 6 ounces
Mathematics
1 answer:
enyata [817]3 years ago
7 0
For large sample confidence intervals about the mean you have: 

xBar ± z * sx / sqrt(n) 

where xBar is the sample mean z is the zscore for having α% of the data in the tails, i.e., P( |Z| > z) = α sx is the sample standard deviation n is the sample size
 
We need only to concern ourselves with the error term of the CI, In order to find the sample size needed for a confidence interval of a given size.

z * sx / sqrt(n) = width. 

so the z-score for the confidence interval of .98 is the value of z such that 0.01 is in each tail of the distribution. z = 2.326348 

The equation we need to solve is:
z * sx / sqrt(n) = width 
n = (z * sx / width) ^ 2. 
n = ( 2.326348 * 6 / 3 ) ^ 2 
n = 21.64758 

Since n must be integer valued we need to take the ceiling of this solution.
n = 22 
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PLEASE HELP!!! BRAINLIEST TO CORRECT COMPLETE ANSWER!
notka56 [123]

Answer:

y=16x+1

Step-by-step explanation:

You want to find the equation for a line that passes through the two points:

(1,17) and (2,33).

First of all, remember what the equation of a line is:

y = mx+b

Where:

m is the slope, and

b is the y-intercept

First, let's find what m is, the slope of the line...

The slope of a line is a measure of how fast the line "goes up" or "goes down". A large slope means the line goes up or down really fast (a very steep line). Small slopes means the line isn't very steep. A slope of zero means the line has no steepness at all; it is perfectly horizontal.

For lines like these, the slope is always defined as "the change in y over the change in x" or, in equation form:

So what we need now are the two points you gave that the line passes through. Let's call the first point you gave, (1,17), point #1, so the x and y numbers given will be called x1 and y1. Or, x1=1 and y1=17.

Also, let's call the second point you gave, (2,33), point #2, so the x and y numbers here will be called x2 and y2. Or, x2=2 and y2=33.

Now, just plug the numbers into the formula for m above, like this:

m=  

33 - 17/  2 - 1

or...

m=  16/ 1

or...

m=16

So, we have the first piece to finding the equation of this line, and we can fill it into y=mx+b like this:

y=16x+b

Now, what about b, the y-intercept?

To find b, think about what your (x,y) points mean:

(1,17). When x of the line is 1, y of the line must be 17.

(2,33). When x of the line is 2, y of the line must be 33.

Because you said the line passes through each one of these two points, right?

Now, look at our line's equation so far: y=16x+b. b is what we want, the 16 is already set and x and y are just two "free variables" sitting there. We can plug anything we want in for x and y here, but we want the equation for the line that specfically passes through the two points (1,17) and (2,33).

So, why not plug in for x and y from one of our (x,y) points that we know the line passes through? This will allow us to solve for b for the particular line that passes through the two points you gave!.

You can use either (x,y) point you want..the answer will be the same:

(1,17). y=mx+b or 17=16 × 1+b, or solving for b: b=17-(16)(1). b=1.

(2,33). y=mx+b or 33=16 × 2+b, or solving for b: b=33-(16)(2). b=1.

See! In both cases we got the same value for b. And this completes our problem.

The equation of the line that passes through the points

(1,17) and (2,33)  is   y=16x+1

4 0
2 years ago
Point D is a fixed point on line PQ such that PD is =DQ, the cordinate of P and Q are (2,3) and (4,7)
Savatey [412]

Answer:

2

Step-by-step explanation:

hope this helps

5 0
3 years ago
What is the 399,713 rounded to the place value of the third underlined digit of 399
maksim [4K]

The <em>correct answer</em> is:

400,000.

Explanation:

The third digit in 399 is 9. To round to this place value, we inspect the digit behind it. If the digit is 5 or greater, we round up; if it is less than 5, we round down.

The digit behind 9 is 7. Since it is greater than 5, we round up. This would ordinarily put the number up 1; however, doing that makes the 9 a 10, which in turn makes the next number 10, and the next number 4. This gives us 400,000.

4 0
3 years ago
Read 2 more answers
How many factors in the expression 8(x +4) (y +4) (z 2 + 4z + 7) have exactly two terms?
Anna11 [10]
From the expression <span>8(x +4) (y +4) (z 2 + 4z + 7),
</span>the factors are 8, (x+4), (y+4), <span>(z^2 + 4z + 7) since each of these factors, when you divide that to the whole expression won't give a remainder</span>
4 0
3 years ago
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Rachel solved 50 problems of her Homework correctly and scored 62.5%. How many problems were there in the Homework?
maria [59]

Answer:

80

Step-by-step explanation:

50 problems/x total = 62.5%

50/62.5=0.8 problem for each percent

0.8 * 100 percent = 80 problems

3 0
3 years ago
Read 2 more answers
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