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3 years ago

Which statement is false?

Mathematics

2 answers:

DochEvi [55]3 years ago

7 0

Answer:

Step-by-step explanation:

lana66690 [7]3 years ago

3 0

Answer:

b is wrong ........

Step-by-step explanation:

I need 20 character long ans

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An item is regularly priced at $60 . It is on sale for 20% off the regular price. How much (in dollars) is discounted from the r

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HELP ME OUTT PPL (BRAINIEST)

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(0, 6)

Step-by-step explanation:

Point T is at (3, 4), and three units to the left would be (0, 4). They then tell us to go two points up, which would change the ordered pair to (0, 6).

I hope this was helpful! Have a lovely day! :D

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2 years ago

The graph on the right shows the theoretical probability of getting a given number heads and 10 flips of a fair coin. If this ex

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approximately, what is the probability of getting 4, 5, 6 heads? : 65%

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4 years ago

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When I double my number, add three, subtract my number, and subtract one, I get my number plus two.

Umnica [9.8K]

Answer:1=1

Step-by-step explanation:Let your no.= x

double the number=2x

add 4 = 2x+4

subtract same number=2x+4-x

subtract 3=2x+4-x-3

I get my number plus 1=x+1

so equation we get

2x+4-x-3=x+1

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So your number can be any real number

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3 years ago

In a study of the effect of cooling rate on the hardness of welded joints, 50 welds cooled at a rate of 10°C/s had an average Ro

Studentka2010 [4]

Answer:

a) The 95% confidence interval would be given by $-1.887 \leq \mu_1 -\mu_2 \leq 2.687$

b) No contradict the result obtained since the confidence interval contains the value 0, so we don't have enough evidence to conclude that we have a significant effect in the colling rate and the hardness.

Step-by-step explanation:

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".

$\bar X_1 =91.1$ represent the sample mean 1

$\bar X_2 =90.7$ represent the sample mean 2

n1=50 represent the sample 1 size

n2=40 represent the sample 2 size

$s_1 =6.55$ sample standard deviation for sample 1

$s_2 =4.32$ sample standard deviation for sample 2

$\mu_1 -\mu_2$ parameter of interest.

Part a

The confidence interval for the difference of means is given by the following formula:

$(\bar X_1 -\bar X_2) \pm t_{\alpha/2}\sqrt{\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}$ (1)

The point of estimate for $\mu_1 -\mu_2$ is just given by:

$\bar X_1 -\bar X_2 =91.1-90.7=0.4$

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

$df=n_1 +n_2 -1=50+40-2=88$

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(0.025,88)".And we see that $t_{\alpha/2}=1.987$

The standard error is given by the following formula:

$SE=\sqrt{\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}$

And replacing we have:

$SE=\sqrt{\frac{6.55^2}{50}+\frac{4.32^2}{40}}=1.325$

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

$0.4-1.987\sqrt{\frac{6.55^2}{50}+\frac{4.32^2}{40}}=-1.887$

$0.4+1.987\sqrt{\frac{6.55^2}{50}+\frac{4.32^2}{40}}=2.687$

So on this case the 95% confidence interval would be given by $-1.887 \leq \mu_1 -\mu_2 \leq 2.687$

Part b

No contradict the result obtained since the confidence interval contains the value 0, so we don't have enough evidence to conclude that we have a significant effect in the colling rate and the hardness.

3 0

3 years ago