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mars1129 [50]
3 years ago
12

PLEASE HELP ASAP

Mathematics
1 answer:
Ksenya-84 [330]3 years ago
3 0
<span>Real numbers are "closed" under addition Integers are "not closed" under division. Irrational numbers are "not closed" under multiplication. Rational numbers are "closed" under subtraction. If an operation is closed under a set of numbers that means that the result of the operation will always be within that same set of numbers. If that's not true, then the operation is not closed. So with that in mind, let's look at the problems. Real numbers are (closed,not closed) under addition * Since a real number plus a real number always results in another real number, then real numbers are closed under addition. So the answer is "closed" Integers are ( closed, not closed) under division. * Let's try this counter example. 1 divided by 2 = 1/2. 1/2 is NOT an integer, therefore integers are not closed under division. The answer is "not closed" Irrational numbers are (closed, not closed) under multiplication. * This is a tricky one. You may give an impulsive answer and say "closed". After all, how could you possibly multiply one non repeating infinite sequence by another and get something rational?. But what's pi multiplied by the reciprocal of pi? Both pi and 1/pi are irrational. Yet when you multiply them together you get 1 which is quite rational. So the answer is "not closed" Rational numbers are ( closed, not closed) under subtraction. * Since rational numbers are all numbers that can be expressed as a fraction consisting on an integer numerator and divisor, we can express subtraction as a/b - c/d = ad/bd - bc/bd = (ad-bc)/bd and since all we're doing is adding, subtracting, and multiplying integers which is closed under those operations, that means that rational numbers are also closed under subtraction. So the answer is "closed".</span>
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Calculate the missing length for this cylinder
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I assume by the length you mean height so,

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A random sample of 49 measurements from one population had a sample mean of 15, with sample standard deviation 5. An independent
kotykmax [81]

Answer:

Comparing the p value with the significance level \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and the difference between the two groups is significantly different.  

Step-by-step explanation:

\bar X_{1}=15 represent the mean for sample 1

\bar X_{2}=18 represent the mean for sample 2

s_{1}=5 represent the sample standard deviation for 1  

s_{f}=6 represent the sample standard deviation for 2  

n_{1}=49 sample size for the group 2  

n_{2}=64 sample size for the group 2  

\alpha=0.01 Significance level provided

t would represent the statistic (variable of interest)  

Concepts and formulas to use  

We need to conduct a hypothesis in order to check if the difference in the population means, the system of hypothesis would be:  

Null hypothesis:\mu_{1}-\mu_{2}=0  

Alternative hypothesis:\mu_{1} - \mu_{2}\neq 0  

We don't have the population standard deviation's, so for this case is better apply a t test to compare means, and the statistic is given by:  

t=\frac{(\bar X_{1}-\bar X_{2})-\Delta}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}} (1)

And the degrees of freedom are given by df=n_1 +n_2 -2=49+64-2=111  

t-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

With the info given we can replace in formula (1) like this:  

t=\frac{(15-18)-0}{\sqrt{\frac{5^2}{49}+\frac{6^2}{64}}}}=-2.897

P value

Since is a bilateral test the p value would be:  

p_v =2*P(t_{111}  

Comparing the p value with the significance level \alpha=0.01 we see that p_v so we can conclude that we have enough evidence to reject the null hypothesis, and the difference between the two groups is significantly different.  

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3 years ago
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Likurg_2 [28]

Answer:

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Step-by-step explanation:

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Lostsunrise [7]

Answer:

Step-by-step explanation:

Applying logarithm rule

Log A - Log B= Log(A/B). Division rule

Now, Logx-log(x+13)=1

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Assume that the log is a natural log whose base is 10.

Then apply logarithm law

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This implies that

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3 0
3 years ago
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