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Rus_ich [418]
3 years ago
7

Carla and Rob left a 20% tip after having lunch at a restaurant. The amount of the tip was $6. Carla's lunch cost $15. Write an

equation you can use to find x, the cost of Rob's lunch.​
Mathematics
1 answer:
Rufina [12.5K]3 years ago
3 0

Answer:

20/100 = 6/15

Step-by-step explanation:

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The Information Technology Department at a large university wishes to estimate the proportion of students living in the dormitor
nadya68 [22]

Answer:

n=\frac{0.5(1-0.5)}{(\frac{0.05}{1.96})^2}=384.16  

And rounded up we have that n=385

Step-by-step explanation:

Previous concepts

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".  

Solution to the problem

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 99% of confidence, our significance level would be given by \alpha=1-0.99=0.01 and \alpha/2 =0.005. And the critical value would be given by:

z_{\alpha/2}=-2.58, z_{1-\alpha/2}=2.58

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 0.05 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)  

We can use as an estimator for p \hat p =0.5. And replacing into equation (b) the values from part a we got:

n=\frac{0.5(1-0.5)}{(\frac{0.05}{1.96})^2}=384.16  

And rounded up we have that n=385

3 0
3 years ago
Lisa says that 43 is an odd number that is composite . Is she correct? Explain.
Assoli18 [71]

Lisa is incorrect although it is an odd number it is not composite. It only has itself and 1. Therefore its a prime number.

This is the definition for prime if you still dont understand.

A prime number is a whole number greater than 1 whose only factors are 1 and itself.

6 0
2 years ago
Read 2 more answers
A circle is divided into 9 equal parts. What is the angle measure of three of those parts ?
Anna11 [10]
1 becuse you put the deniminatoe 1
8 0
3 years ago
According to a report by Scarborough Research, the average monthly household cellular phone bill is $73. Suppose local monthly h
marta [7]

Answer:

The probability that a randomly selected monthly cell phone bill is less than $95 is 0.9772

Step-by-step explanation:

The average monthly household cellular phone bill is $73.

\mu = 73

Local monthly household cell phone bills are normally distributed with a standard deviation of $11.

\sigma = 11

We are supposed to find the probability that a randomly selected monthly cell phone bill is less than $95 i.e.P(x<95)

Z=\frac{x-\mu}{\sigma}

Z=\frac{95-73}{11}

Z=2

Refer the z table for p value

So,p value = 0.9772

Hence the probability that a randomly selected monthly cell phone bill is less than $95 is 0.9772

4 0
3 years ago
You and two friends are making a gift basket. You want to keep the cost below $15 per person. Write and solve a inequality that
elena-14-01-66 [18.8K]
C < or = to $45

Theres no less than/equal to button on my phone
5 0
2 years ago
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