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Misha Larkins [42]

3 years ago

7

The price of an mp3 player is reduced to three-fourths of its original price. The new price is $75. What is the the original pri

ce of the MP3 player ?

1 answer:

elena55 [62]3 years ago

7 0

Answer:

idk

Step-by-step explanation:

i just want the points my dood

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Please show work if you do, ( and get it right) I will make you brainliest!!!

DerKrebs [107]

Answer:

The percentage increase in bird population in the second years is 4% .

Step-by-step explanation:

Given as :

During two years, the population of birds of an island became 7 times more than before.

The the percentage increase in first year = = $r_1$ =40%

Let The percentage increase in second year = $r_2$ = r%

So, According to question

The initial population of bird = x

The increase population of bird =7 times before = 7 x

Now,

The increase population of bird = initial population of bird × (1+ $\dfrac{r_1}{100}$ ) × (1+ $\dfrac{r_2}{100}$ )

Or, 7 x = x × (1+ $\dfrac{40}{100}$ ) × (1+ $\dfrac{r}{100}$ )

Or, $\dfrac{7 x}{x}$ = 1.4 × (1+ $\dfrac{r}{100}$ )

Or, 7 = 1.4 × (1+ $\dfrac{r}{100}$ )

Or, $\dfrac{7 }{1.4}$ = (1+ $\dfrac{r}{100}$ )

Or, 5 = (1+ $\dfrac{r}{100}$ )

Or, (1+ $\dfrac{r}{100}$ ) = 5

Or, $\dfrac{r}{100}$ = 5 - 1

Or, $\dfrac{r}{100}$ = 4

∴ r = 4 × 100

I.e r = 400

so, The percentage increase = r% = 4

Hence The percentage increase in bird population in the second years is 4% . Answer

3 0

3 years ago

What is the volume of a cone with a radius of 2 and a height of 19?

kykrilka [37]

Remember that the cone volume formula is $V=\pi r^2\frac{h}{3}$ , with r = radius and h = height. Using our information, we can form our equation as such: $V=\pi 2^2\frac{19}{3}$ (I'll be keeping the answer in pi form.)

Firstly, solve the exponents: $V=\pi 4\frac{19}{3}$

Next, multiply 4 and 19/3 together and your answer should be (rounded to the hundreths): V = 25.33π un^3

5 0

3 years ago

Read 2 more answers

The number of events is 29, the number of trials is 298, the claimed population proportion is 0.10, and the significance leve

Nina [5.8K]

Answer:

$z=\frac{0.0973 -0.1}{\sqrt{\frac{0.1(1-0.1)}{298}}}=-0.155$

$p_v =2*P(Z$

And we can use excel to find the p value like this: "=2*NORM.DIST(-0.155;0;1;TRUE)"

So the p value obtained was a very high value and using the significance level given $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the proportion of interest is not significantly different from 0.1 .

Step-by-step explanation:

1) Data given and notation

n=298 represent the random sample taken

X=29 represent the events claimed

$\hat p=\frac{29}{298}=0.0973$ estimated proportion

$p_o=0.1$ is the value that we want to test

$\alpha=0.05$ represent the significance level

Confidence=95% or 0.95

z would represent the statistic (variable of interest)

$p_v$ represent the p value (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to test the claim that the proportion is 0.1 or no.:

Null hypothesis: $p=0.1$

Alternative hypothesis: $p \neq 0.1$

When we conduct a proportion test we need to use the z statistic, and the is given by:

$z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}$ (1)

The One-Sample Proportion Test is used to assess whether a population proportion $\hat p$ is significantly different from a hypothesized value $p_o$ .

3) Calculate the statistic

Since we have all the info requires we can replace in formula (1) like this:

$z=\frac{0.0973 -0.1}{\sqrt{\frac{0.1(1-0.1)}{298}}}=-0.155$

4) Statistical decision

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.

The next step would be calculate the p value for this test.

Since is a bilateral test the p value would be:

$p_v =2*P(Z$

And we can use excel to find the p value like this: "=2*NORM.DIST(-0.155;0;1;TRUE)"

So the p value obtained was a very high value and using the significance level given $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the proportion of interest is not significantly different from 0.1 .

We can do the test also in R with the following code:

> prop.test(29,298,p=0.1,alternative = c("two.sided"),conf.level = 1-0.05,correct = FALSE)

7 0

2 years ago

The perimeter of a rectangle is 24 in.and its length is 3times its width. What are the length and width of ThE rectangle?

Mama L [17]

let w = width and 3w = length

perimeter is the distance around the outside of the object or P = 2L + 2W

2(3w) + 2w = 24

6w + 2w= 24

8w = 24

w= 3

3w= 9

Width is 3in. and length is 9in.

8 0

3 years ago

Read 2 more answers

the table shows the balance of a money market account over time. write a function that represents the balancr y (in dollars) aft

Solnce55 [7]

Answer:

y = 1500 * 1.09^t

Step-by-step explanation:

It should be clear that the rate of change is non-linear, meaning that we can express the function in the following manner

y = a * b^t, where a is the initial value and b is the rate of change and t is how many years.

Well, year 0 is the rate of change so we can say that a = 1500

Next, we divide any two consecutive year balances to find our rate of change:

1635/1500 = 1.09

Therefore, our equation looks like this: y = 1500 * 1.09^t

6 0

2 years ago