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cestrela7 [59]
3 years ago
15

Suppose a lawn and garden company wants to determine the current percentage of customers who use fertilizer on their lawns. How

many customers should the company survey in order to be 95% confident that the estimated (sample) proportion is within 4 percentage points of the true population proportion of customers who use fertilizer on their lawns?
Mathematics
1 answer:
marishachu [46]3 years ago
3 0

Answer:

n=601

Step-by-step explanation:

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 population proportion have the following distribution

p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. And the critical value would be given by:

z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96

The confidence interval for the mean is given by the following formula:  

\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}

The margin of error for the proportion interval is given by this formula:  

ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}    (a)  

And on this case we have that ME =\pm 0.04 and we are interested in order to find the value of n, if we solve n from equation (a) we got:  

n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}   (b)  

Since we don't have a prior estimation for the proportion we can use 0.5 as estimation. And replacing into equation (b) the values from part a we got:

n=\frac{0.5(1-0.5)}{(\frac{0.04}{1.96})^2}=600.25  

And rounded up we have that n=601

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Give an example of when and why one would use a continuity correction factor?
iris [78.8K]

Answer:

An example of when a continuity correction factor can be used is in finding the number of tails in 50 tosses of a coin within a given range .

and continuity correction factor is used when a continuous probability distribution is used on a discrete probability distribution

Step-by-step explanation:

An example of when a continuity correction factor can be used is in finding the number of tails in 50 tosses of a coin within a given range .

continuity correction factor is used when a continuous probability distribution is used on a discrete probability distribution,  continuity correction factor creates an adjustment on a discrete distribution while using a continuous distribution

3 0
3 years ago
The line passes through the points ( 7, -7) and ( 6, -5) a. y = -2x + 7 c. y = -2x - 7 b. y = 2x - 21 d. y = 2x - 7
ollegr [7]
Slope = (-5+7)/(6 - 7) = -2

y = mx + b
b = y - mx
b = -7 - (-2)(7)
b = -7 + 14
b = 7

equation
y = -2x + 7

answer
<span>a. y = -2x + 7</span>
5 0
3 years ago
Two cards are drawn without replacement from a standard deck of cards. What is the probability that the second one is a black ca
forsale [732]

Answer:

The probability is 169/2652

Step-by-step explanation:

The number of cards in a deck of cards is 52

In each deck of cards, there are 13 black cards and 13 spade cards

The probability of selecting a spade card will be;

13/52 = 1/4

Without replacement, we are left with 51 cards and the probability of selecting a black card will now be 13/51

So the probability of the second card being a black card if the first is spade will be ;

13/52 * 13/51

= 169/2,652

4 0
2 years ago
Identify as a direct variation, inverse variation or neither. The number of tons of coal burned by an old coal burning locomotiv
pochemuha
Answer: it is a direct variation.

Justification:

In a direct variation the variables are related by a proportionality constant in this way:

y = k x

Tthan means that the value of y is always the product of a constant times the value of x.

The situation discribed for the coal may be written as:
number of tons of coal burned: c

number of hours: h

⇒ c = k × h

Which is that you can calcualte the number of tons of coal burned at any time, once you know the proportionality constant k.




5 0
3 years ago
a dress shirt that normally cost $38.50 is on sale and being advertised as a 30% decrease. what percent expression could be used
astraxan [27]

.7 * 38.5 = original price

.7 * 38.5 = $26.95

4 0
2 years ago
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