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2 years ago

What is the r-value of the following data to three decimal places?

Mathematics

2 answers:

ValentinkaMS [17]2 years ago

7 0

Answer:

Option B

Step-by-step explanation:

Given that two variables in table as

Total Average

x 2 6 7 8 12 35 7

y 15 13 9 8 5 50 10

xy 30 78 63 64 60 295 59

(x-7)^2 25 1 0 1 25 52 10.4

(y-10)^2 25 9 1 4 25 64 12.8

Var x = 10.4 and std dev x = 3.225

Var Y = 12.8 and std dev Y = 3.578

Cov (xy) = E(xy)-E(x) E(Y)=59-70=-11

Correlation coefficient r

= Cov /sx sy = -11/(3.225)(3.578)=-0.9532

Round off to get

r=-0.953

Henceoption B is right.

Ann [662]2 years ago

3 0

Answer:

B. -0.953

Step-by-step explanation:

Apex

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The manufacturer of hardness testing equipment uses steel-ball indenters to penetrate metal that is being tested, however, the m

masha68 [24]

Answer:

$1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789$

$1.667+2.31\frac{1.803}{\sqrt{9}}=3.055$

So on this case the 95% confidence interval would be given by (0.2789;3.055)

The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

Step-by-step explanation:

We have the following dataset:

specimen 1 2 3 4 5 6 7 8 9

Steel Ball 51 57 61 70 68 54 65 51 53

Diamond 53 55 63 74 69 56 68 51 56

If we calculate the differences diamond-steel ball we have this datase:

d: 2, -2, 2, 4, 1, 2, 3, 0, 3

The second step is calculate the mean difference

$\bar d= \frac{\sum_{i=1}^n d_i}{n}=1.667$

The third step would be calculate the standard deviation for the differences, and we got:

$s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1} =1.803$

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

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:

$df=n-1=9-1=8$

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(0.025,9)".And we see that $t_{\alpha/2}=2.31$ .

Now we have everything in order to replace into formula (1):

$1.667-2.31\frac{1.803}{\sqrt{9}}=0.2789$

$1.667+2.31\frac{1.803}{\sqrt{9}}=3.055$

So on this case the 95% confidence interval would be given by (0.2789;3.055)

The 95% confidence interval to judge whether the two indeners result in different measurements is?

Yes the confidence interval not contains the value 0 so we can conclude that the values for Diamond are significantly higher than the values for Steel Ball at 5% of significance.

4 0

2 years ago

The rectangular playground in tim's school is three times as long as it is wide. the area of the playground is 75 square meters.

qwelly [4]

Let x be the width of the playground, then 3x is the length of the
<span>playground

х * 3х = 75
3x</span>² = 75
x² = 25
x = 5 m (width)
5*3=15 m (length)

Perimeter = 2(5+15) = 2*20 = 40 meters.

8 0

2 years ago

Question 2 (1 point)

hichkok12 [17]

Answer:

Rebecca does not have a return yet because the stock was not sold since there was a limit order at $33.

However, the value of her investment can be put around $2,400 (100 x $24 average price).

Step-by-step explanation:

Price of Havad Stock bought a year ago = $20

No. of shares = 100

Limit order selling price = $33

Stock prices during the limit order day = $23, $26, and $22

The stock cannot be sold, since its price did not reach $33.

Rebecca's limit order is an order to buy or sell her stock in Havad at $33 or better. Since her order is a sell limit order, it can only be executed at the limit price of $33 or higher. Unfortunately, the price of the stock did not reach the limit order on that particular day. This implies that her limit order is not guaranteed to execute.

8 0

1 year ago

Ian has 12.2 ounce bottle of ketchip. He uses 1/20 of the ketchup every time he has a buffalo burger How many ounces of ketchup

tatiyna

If Ian uses 1/20 of the ketchup 4 times, this is equal to 4/20, or $\frac{4}{20}$ .

$\frac{4}{20}$ can be simplified to $\frac{1}{5}$ , which means we need to work out $\frac{1}{5}$ of 12.2

$\frac{1}{5}$ is equivalent to 20%, which as a decimal is 0.2

0.2 x 12.2 = 2.44 - however, this is how much he has used, and we need to figure out how much is left.

12.2 - 2.44 = 9.76

So, Ian has 9.76 oz remaining :)

4 0

2 years ago

Which of the following is the least reduced equivalent of 243/729?

Vladimir79 [104]

Answer:

1/9

Step-by-step explanation:

243/729 to it's equivalent fraction is

243/729 divide numerator and the denominator by 3 = 81/243

81/243 divide numerator and denominator by 3 =27/81

27/81 divide both numerator and denominator by 3 =9/81

9/81 divide both numerator and denominator by 9 =1/9

answer = 1/9

Therefore, 243/729 reduced to it's equivalent fraction is = 1/9

7 0

1 year ago