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2 years ago

7

Your friends ate at a restaurant and left a $2.40 tip. They left a 15% tip. What was the cost of their bill before the tip?

2 answers:

postnew [5]2 years ago

5 0

16
To show work divide 2.4 by 3 to get .8 then multiply it by 20 to get 16

zhannawk [14.2K]2 years ago

3 0

Answer:

16$ is the bill

Step-by-step explanation:

so 2.40 is 15% of the bill, what i'd do is first divide 2.40(15%) by 3 to get 5% which can make this much easier, 2.40÷3=0.80. this means that 1.60 is 10% since 0.80 is 5%. so now we do 1.60×10=16$

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Suppose that the epidemiologist wants to re-estimate the population proportion and wishes for her 95% confidence interval to hav

Svetllana [295]

Answer:

She needs a sample of at least 385.

Step-by-step explanation:

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$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

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The margin of error is:

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So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

How large a sample should she take to achieve this?

She needs a sample of size at least n.

n is found when M = 0.04.

We do not know the true population proportion, so we use $\pi = 0.5$ , which is the case for which we are going to need the largest sample size.

$M = z\sqrt{\frac{\pi(1-\pi)}{n}}$

$0.05 = 1.96\sqrt{\frac{0.5*0.5}{n}}$

$0.05\sqrt{n} = 1.96*0.5$

Dividing both sides by 0.05

$\sqrt{n} = 19.6$

$(\sqrt{n})^{2} = 19.6^{2}$

$n = 384.2$

Rounding up

She needs a sample of at least 385.

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Answer:

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Step-by-step explanation:

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