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sineoko [7]
3 years ago
9

If 30% of a number is 15, what is 25% of the number?

Mathematics
1 answer:
Scorpion4ik [409]3 years ago
3 0

Answer:

12.5

Step-by-step explanation:

Basically, the number was multiplied by .3 to get 15. So if you do 15/.3 you'll get your original number which is 50. Then you multiply by .25 and get 12.5.

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Alex787 [66]
A=p(1+i/m)^mn
Interest earned
I=A-p

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A=1,456.23

I=1,456.23−980
I=476.23

A=7,200×(1+0.04)^(8)
A=9,853.69

I=9,853.69−7,200
I=2,653.69

A=15,520×(1+0.06÷2)^(2×4)
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I=19,660.27−15,520
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5 0
3 years ago
An article reported that for a sample of 52 kitchens with gas cooking appliances monitored during a one-week period, the sample
kolbaska11 [484]

Answer:

a) 654.16-2.01\frac{164.55}{\sqrt{52}}=608.29    

654.16+2.01\frac{164.55}{\sqrt{52}}=700.03    

And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm

b) n=(\frac{1.960(175)}{25})^2 =188.23 \approx 189

Step-by-step explanation:

Part a

The confidence interval for the mean is given by the following formula:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}   (1)

In order to calculate the critical value t_{\alpha/2} we need to find first the degrees of freedom, given by:

df=n-1=52-1=51

Since the Confidence is 0.95 or 95%, the value of \alpha=0.05 and \alpha/2 =0.025, and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.025,51)".And we see that t_{\alpha/2}=2.01

Replacing we got:

654.16-2.01\frac{164.55}{\sqrt{52}}=608.29    

654.16+2.01\frac{164.55}{\sqrt{52}}=700.03    

And we can conclude that we are 95% confident that the true mean of Co2 level is between 608.29 and 700.03 ppm

Part b

The margin of error is given by :

ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}    (a)

The desired margin of error is ME =50/2=25 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

n=(\frac{z_{\alpha/2} s}{ME})^2   (b)

The critical value for 95% of confidence interval now can be founded using the normal distribution. And in excel we can use this formla to find it:"=-NORM.INV(0.025;0;1)", and we got z_{\alpha/2}=1.960, and we use an estimator of the population variance the value of 175 replacing into formula (b) we got:

n=(\frac{1.960(175)}{25})^2 =188.23 \approx 189

6 0
3 years ago
How do you multiply variables with negative expontents?
blsea [12.9K]

Answer:

z4/x3y2

Step-by-step explanation:

apply the product to a power rule

power rule

negative exponents

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3 years ago
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Question 9

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Question 10

Correct Number: 5

Incorrect Number: 6

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2 years ago
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