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1 year ago

9

The amount of money that is left in a medical savings account is expressed by the equation y = negative 24 x + 379, where x repr

esents the number of weeks and y represents the amount of money, in dollars, that is left in the account. After how many weeks will the account have $67 left in it?

1 answer:

Alekssandra [29.7K]1 year ago

3 0

$67 = -24x + 379\\$

Subtract 379 from both sides.

that gives us: $-312 = -24x$

divide both sides by -24 which equals: x = 13.

13 weeks

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2 years ago

A large city in the ancient world was square-shaped. measured in miles, its area numerically exceeded its perimeter by about 132

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Area = perimeter + 132.

Let each side of the city be x miles long, then:-

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x = 13.66, -9.66 We ignore the negative

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1 year ago

The U.S. Energy Information Administration (US EIA) reported that the average price for a gallon of regular gasoline is $2.94. T

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Answer:

a) 25

b) 67

c) 97

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.025 = 0.975$ , so $z = 1.96$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample. In this problem, $\sigma = 0.25$

(a) The desired margin of error is $0.10.

This is n when M = 0.1. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.1 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.1\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.1}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.1})^{2}$

$n = 24.01$

Rounding up to the nearest whole number, 25.

(b) The desired margin of error is $0.06.

This is n when M = 0.06. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.06 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.06\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.06}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.06})^{2}$

$n = 66.7$

Rounding up, 67

(c) The desired margin of error is $0.05.

This is n when M = 0.05. So

$M = z*\frac{\sigma}{\sqrt{n}}$

$0.05 = 1.96*\frac{0.25}{\sqrt{n}}$

$0.05\sqrt{n} = 1.96*0.25$

$\sqrt{n} = \frac{19.6*0.25}{0.05}$

$(\sqrt{n})^{2} = (\frac{19.6*0.25}{0.05})^{2}$

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8 0

1 year ago

Tony addison obtained a 20-year, $45,000 mortgage loan from united savings with an interest rate of 8.5%. his monthly payment is

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As given,

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And for 1st month it will be = $\frac{3825}{12}$ = $318.75

As given, the first month's payment is $390.60 and this covers the interest Additional amount ($390.60 - $318.75 = $71.85) is a payment against the principle.

Hence, the new principle after the 1st month is $71.85 less than $45000

= 45000-71.85 = $44928.15

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1 year ago

What interest will be earned if $6300 is invested for 3 years at 12% compounded monthly? Write your answer rounded to the neare

Butoxors [25]

Answer:
Interest earned = 2713.8

Explanation:
We will solve this problem on two steps:
1- get the final amount after three years
2- get the interest earned by subtracting the initial amount from the final one.

1- getting the final amount after 3 years:
The formula that we will use is as follows:
A = P (1 + r/n)^(nt)
where:
A is the final amount we want to calculate
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r is the interest = 0.12
n is the number of compounds per year =12
t is time in years = 3

Substitute to get the final amount:
A = P (1 + r/n)^(nt)
A = 6300 (1 + 0.12/12) ^ (12*3)
A = 9013.8

2- getting the interest earned:
Interest earned = final amount - initial amount
Interest earned = 9013.8 - 6300
Interest earned = 2713.8

Hope this helps :)

7 0

1 year ago

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