Please help me with this

A refrigerator costs $580 a year to run. A family purchases a new one for $1200 that will save them 22% annually in energy costs

NeTakaya

Answer:

It will take nine years and four months for the refrigerator to pay for itself.

Step-by-step explanation:

The new refrigerator which costs $1200, saves the family 22% annually in energy cost.

Since the old refrigerator costs $580 to run, we want to determine how many years it will take for 22% of $580 per year to make $1200.

22% of $580

= 580 × 0.22

= 127.6

That is, it saved then $127.6 per year.

Now,

$1200/127.6

≈ 9.4

Which means, it will take 9 years and 4 months for the refrigerator to pay for itself.

7 0

3 years ago

Select all simplified expressions of 3^4 ÷ 3^9. 3^13 3^5 1/243 1/3^5 1^5

zloy xaker [14]

1/3^5

Explanation
Subtract the exponents
Since the exponent is negative
It stays in the bottom hence why the one is added

5 0

3 years ago

A college entrance exam company determined that a score of 2323 on the mathematics portion of the exam suggests that a student i

aleksandrvk [35]

Answer:

a) The null and alternative hypothesis are:

$H_0: \mu=23\\\\H_a:\mu> 23$

c) Test statistic t=1.53

P-value=0.064

d) The null hypothesis failed to be rejected.

There is not enough evidence to support the claim that students who complete the core curriculum are ready for college-level mathematics. That is that the true score for the group is not significantly higher than 23.

Step-by-step explanation:

The question is incomplete:

a) State the appropriate null and alternative hypotheses.

c) Use the P-value approach at the 0.05 level of significance to test the hypotheses in part (a). ldentify the test statistic. (Round to two decimal places as needed.) Identfy the P-value. P-value (Round to three decimal places as needed.)

d) Write a conclusion based on the results. Choose the correct answer below. ? the null hypothesis and claim that there ? sufficient evidence to conclude that the population mean is ? than 20.

This is a hypothesis test for the population mean.

The claim is that students who complete the core curriculum are ready for college-level mathematics.

Then, the null and alternative hypothesis are:

$H_0: \mu=23\\\\H_a:\mu> 23$

The significance level is assumed to be 0.05.

The sample has a size n=150.

The sample mean is M=23.4.

As the standard deviation of the population is not known, we estimate it with the sample standard deviation, that has a value of s=3.2.

The estimated standard error of the mean is computed using the formula:

$s_M=\dfrac{s}{\sqrt{n}}=\dfrac{3.2}{\sqrt{150}}=0.261$

Then, we can calculate the t-statistic as:

$t=\dfrac{M-\mu}{s/\sqrt{n}}=\dfrac{23.4-23}{0.261}=\dfrac{0.4}{0.261}=1.531$

The degrees of freedom for this sample size are:

$df=n-1=150-1=149$

This test is a right-tailed test, with 149 degrees of freedom and t=1.531, so the P-value for this test is calculated as (using a t-table):

$P-value=P(t>1.531)=0.064$

As the P-value (0.064) is bigger than the significance level (0.05), the effect is not significant.

The null hypothesis failed to be rejected.

There is not enough evidence to support the claim that students who complete the core curriculum are ready for college-level mathematics.

6 0

3 years ago

Diego then says if we take half the first number and double the second the sum is 14. write an equation that could represent thi

Anon25 [30]

x = the first number

(x/2)² = 14

Hope this helps!

Can I get brainliest? thanks.

5 0

3 years ago

Which of the following is the complete list of roots for the polynomial function f (x) = (x squared 6 x 8) (x squared 6 x 13)? –

Sunny_sXe [5.5K]

The roots of the given polynomial function is {-4, -2, -3 + 2i, -3 - 2i}.

<h3>How to get the roots of the polynomial?</h3>

Here we have the polynomial function:

$f(x) = (x^2 + 6x + 8)*(x^2 + 6x + 13)$

So we just need to find the roots of the two quadratic functions, to do that, we use Bhaskara's formula.

For the first one, we have:

$x = \frac{-6 \pm \sqrt{6^2 - 4*8} }{2} \\\\x = \frac{-6 \pm 2}{2}$

So the two solutions are:

x = (-6 - 2)/2 = -4

x = (-6 + 2)/2 = -2

For the second quadratic we have:

$x = \frac{-6 \pm \sqrt{6^2 - 4*13} }{2} \\\\x = \frac{-6 \pm 4i}{2}$

So the two solutions are:

x = -3 + 2i

x = -3 - 2i

Finally, the list is:

{-4, -2, -3 + 2i, -3 - 2i}

If you want to learn more about polynomials:

brainly.com/question/4142886

#SPJ4

8 0

3 years ago