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3 years ago

Which of the following expressions could give the total amount of a $45 restaurant bill with a 15% tip added on?

Mathematics

1 answer:

vazorg [7]3 years ago

4 0

Answer:

$51.75

Step-by-step explanation:

Given

Total amount of bill, x= $45

Tip Percent=15%

⇒15% on $45 is to be paid extra as tip, other than the already paying $45

⇒Tip $=\frac{15}{100}\times x=\frac{15}{100} \times45=6.75$

So total amount to be paid= Bill+ tip

$= x + tip=x+\frac{15}{100} x=1.15x=1.15\times45$

=$51.75

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An SRS of 350 high school seniors gained an average of x¯=21 points in their second attempt at the SAT Mathematics exam. Assume

Lynna [10]

Answer:

a) $21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

b) $ME=2.58\frac{52}{\sqrt{350}}=7.17$

c) $ME=2.58\frac{52}{\sqrt{100}}=13.42$

d) D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

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".

Part a

$\bar X=21$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=52$ represent the population standard deviation

n=350 represent the sample size

99% confidence interval

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

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that $z_{\alpha/2}=2.58$

Now we have everything in order to replace into formula (1):

$21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

Part b

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{350}}=7.17$

Part c

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{100}}=13.42$

Part d

As we can see when we reduce the sample size we increase the margin of error so the best option for this case is:

D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

6 0

3 years ago

Which ordered pairs are solutions to the inequality x+3y≥−8?

crimeas [40]

(-6,0)
(-1,-2)
(-5,-1)

4 0

3 years ago

Read 2 more answers

What is the definition of mean???

Scilla [17]

Mean, in terms of math, is the total added values of all the data in a set divided by the number of data in the set. Make sense? If not, here' an example...

Let's say this is my data set:
1, 2, 5, 4, 3, 8, 7, 4, 6,10

To find the mean...
Step 1: Add all of them together.
1+2+5+4+3+8+7+4+6+10 is what? 50. Now that you have this number...
Step 2: Divide by the amount there are. Basically, count up all of the numbers. How many are there? There are 10. Finally...
Step 3: Divide. 50/10 is 5, so the mean of this data set would be 5. Get it? I sure hoped this helped :)

3 0

3 years ago

Use the graph to evaluate the function. f(-5) = y -8 -6

DENIUS [597]

Answer:

-4

Step-by-step explanation:

Go to x value of -5 and go down until you touch line.

3 0

3 years ago

The area of a square mat is 125 square inches. The best approximation of its length is inches. If the length of each side is inc

gtnhenbr [62]

The area of a square is simply the side length squared and we are given that the area is 125 so:

s^2=125

s=√125

s=5√5

Now using the area equation again, and adding 1 inch to s we have:

A=(s+1)^2, and using s found above we have:

A=(5√5+1)^2

A=125+10√5+1

A=126+10√5 in^2

A≈148.36 in^2 (to nearest hundredth of a square inch)

4 0

3 years ago

Read 2 more answers