1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
DENIUS [597]
2 years ago
14

In order to clear out room for new merchandise, James decided to mark down some of the items for sale in his electronics store.

He marked down DVD players by 36%, and he marked down stereo tuners by 22%. If DVD players cost $41. 60 after the markdown and stereo tuners cost $69. 42 after the markdown, which item’s price was reduced by more, and by how many dollars more was it reduced? Round all dollar values to the nearest cent. A. The DVD player’s price was reduced by $3. 82 more than the stereo tuner’s price. B. The DVD player’s price was reduced by $27. 82 more than the stereo tuner’s price. C. The stereo tuner’s price was reduced by $0. 29 more than the DVD player’s price. D. The stereo tuner’s price was reduced by $27. 53 more than the DVD player’s price.
Mathematics
1 answer:
masya89 [10]2 years ago
4 0

The correct answer is A, as the DVD player's price was reduced by $ 3.82 more than the stereo tuner's price.

In order to clear out room for new merchandise, James decided to mark down some of the items for sale in his electronics store, and he marked down DVD players by 36%, and he marked down stereo tuners by 22%, if DVD Players cost $ 41.60 after the markdown and stereo tuners cost $ 69.42 after the markdown.

To determine which item's price was reduced by more, and by how many dollars more was it reduced, the following calculation must be performed:

  • 100 - 36 = 64
  • 64 = 41.60
  • 100 = X
  • 100 x 41.60 / 64 = X
  • 4160/64 = X
  • 65 = X
  • 65 - 41.60 = 23.40

  • 100 - 22 = 78
  • 78 = 69.42
  • 100 = X
  • 69.42 x 100/78 = X
  • 6942/78 = X
  • 89 = X
  • 89 - 69.42 = 19.58

Therefore, the DVD player's price was reduced by $ 3.82 more than the stereo tuner's price.

Learn more about maths in brainly.com/question/18629331

You might be interested in
A random variable X has a gamma density function with parameters α= 8 and β = 2.
DerKrebs [107]

I know you said "without making any assumptions," but this one is pretty important. Assuming you mean \alpha,\beta are shape/rate parameters (as opposed to shape/scale), the PDF of X is

f_X(x) = \dfrac{\beta^\alpha}{\Gamma(\alpha)} x^{\alpha - 1} e^{-\beta x} = \dfrac{2^8}{\Gamma(8)} x^7 e^{-2x}

if x>0, and 0 otherwise.

The MGF of X is given by

\displaystyle M_X(t) = \Bbb E\left[e^{tX}\right] = \int_{-\infty}^\infty e^{tx} f_X(x) \, dx = \frac{2^8}{\Gamma(8)} \int_0^\infty x^7 e^{(t-2) x} \, dx

Note that the integral converges only when t.

Define

I_n = \displaystyle \int_0^\infty x^n e^{(t-2)x} \, dx

Integrate by parts, with

u = x^n \implies du = nx^{n-1} \, dx

dv = e^{(t-2)x} \, dx \implies v = \dfrac1{t-2} e^{(t-2)x}

so that

\displaystyle I_n = uv\bigg|_{x=0}^{x\to\infty} - \int_0^\infty v\,du = -\frac n{t-2} \int_0^\infty x^{n-1} e^{(t-2)x} \, dx = -\frac n{t-2} I_{n-1}

Note that

I_0 = \displaystyle \int_0^\infty e^{(t-2)}x \, dx = \frac1{t-2} e^{(t-2)x} \bigg|_{x=0}^{x\to\infty} = -\frac1{t-2}

By substitution, we have

I_n = -\dfrac n{t-2} I_{n-1} = (-1)^2 \dfrac{n(n-1)}{(t-2)^2} I_{n-2} = (-1)^3 \dfrac{n(n-1)(n-2)}{(t-2)^3} I_{n-3}

and so on, down to

I_n = (-1)^n \dfrac{n!}{(t-2)^n} I_0 = (-1)^{n+1} \dfrac{n!}{(t-2)^{n+1}}

The integral of interest then evaluates to

\displaystyle I_7 = \int_0^\infty x^7 e^{(t-2) x} \, dx = (-1)^8 \frac{7!}{(t-2)^8} = \dfrac{\Gamma(8)}{(t-2)^8}

so the MGF is

\displaystyle M_X(t) = \frac{2^8}{\Gamma(8)} I_7 = \dfrac{2^8}{(t-2)^8} = \left(\dfrac2{t-2}\right)^8 = \boxed{\dfrac1{\left(1-\frac t2\right)^8}}

The first moment/expectation is given by the first derivative of M_X(t) at t=0.

\Bbb E[X] = M_x'(0) = \dfrac{8\times\frac12}{\left(1-\frac t2\right)^9}\bigg|_{t=0} = \boxed{4}

Variance is defined by

\Bbb V[X] = \Bbb E\left[(X - \Bbb E[X])^2\right] = \Bbb E[X^2] - \Bbb E[X]^2

The second moment is given by the second derivative of the MGF at t=0.

\Bbb E[X^2] = M_x''(0) = \dfrac{8\times9\times\frac1{2^2}}{\left(1-\frac t2\right)^{10}} = 18

Then the variance is

\Bbb V[X] = 18 - 4^2 = \boxed{2}

Note that the power series expansion of the MGF is rather easy to find. Its Maclaurin series is

M_X(t) = \displaystyle \sum_{k=0}^\infty \dfrac{M_X^{(k)}(0)}{k!} t^k

where M_X^{(k)}(0) is the k-derivative of the MGF evaluated at t=0. This is also the k-th moment of X.

Recall that for |t|,

\displaystyle \frac1{1-t} = \sum_{k=0}^\infty t^k

By differentiating both sides 7 times, we get

\displaystyle \frac{7!}{(1-t)^8} = \sum_{k=0}^\infty (k+1)(k+2)\cdots(k+7) t^k \implies \displaystyle \frac1{\left(1-\frac t2\right)^8} = \sum_{k=0}^\infty \frac{(k+7)!}{k!\,7!\,2^k} t^k

Then the k-th moment of X is

M_X^{(k)}(0) = \dfrac{(k+7)!}{7!\,2^k}

and we obtain the same results as before,

\Bbb E[X] = \dfrac{(k+7)!}{7!\,2^k}\bigg|_{k=1} = 4

\Bbb E[X^2] = \dfrac{(k+7)!}{7!\,2^k}\bigg|_{k=2} = 18

and the same variance follows.

6 0
2 years ago
How many 5-digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, if repetitions of digits are allowed?
valentinak56 [21]
50 different 5-digit numbers because it would be 5x10 which equals 50.
5 0
3 years ago
ANYONE PLEASE JUST HELP ME I HAVE ASKED THE SAME QUESTION 3 TIME BUT NO ONE ANSWERS IT. I WILL GIVE BRAINLEST PLEASE JUST HELP M
fenix001 [56]

Answer:

Umm the pic is blocked

Its the blocked picture or meh

Step-by-step explanation:

3 0
3 years ago
Graph a line with a slope of -2/5 That contains the point (-3,5)
love history [14]

put one point on (-3,5) and another point on (2,3)

7 0
3 years ago
What is the exponential regression equation that fits these data? y x 1 4 2 8 3 27 4 85 5 250 6 600
Volgvan

Answer:

its is C because the other ones are obvious wrong. So it has to be C plus i did this test.

Step-by-step explanation:

5 0
3 years ago
Other questions:
  • Choose the ratio that you would use to convert 2.5 centimeters to meters please
    11·2 answers
  • Seventeen students reported how many email accounts they have. The dot plot below shows the data collected: A dot plot is shown
    15·1 answer
  • According to the Old
    9·1 answer
  • Sketch the regions enclosed by the given curves. Decide whether to integrate with respect to x or y. Draw a typical approximatin
    8·1 answer
  • Solve the proportion below. 5/x = 30/72 a.12 b.9 c.6 d.30
    15·2 answers
  • Compute the value of each expression: |−12|−2|−6|
    7·1 answer
  • The owner of a small store buys coats for ​$55.00 each.
    11·2 answers
  • Luna is 12 blocks from school and walk towards the concert at an average speec of 2 blocks per minute. select the equation that
    11·1 answer
  • Determine wether the graph shows a positive correlation, negative correlation, or no correlation. If there is a positive or nega
    11·1 answer
  • Please someone tell me the answer of these questions
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!