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3 years ago

Can someone check my answers

Mathematics

2 answers:

Lelechka [254]3 years ago

8 0

The first image with the answers are right but the second image is blank

Ipatiy [6.2K]3 years ago

6 0

Questions 1–3 are marked correctly. (See your other posting of these questions.)

$\left(\dfrac{5}{3}\right)\left(\dfrac{3}{5}\right)=\dfrac{(5)(3)}{(3)(5)}=\dfrac{(3)(5)}{(3)(5)}\\\\=1\qquad\text{numerator = denominator}$

$\dfrac{2}{5}(-7)\dfrac{5}{2}=\dfrac{(2)(5)}{(2)(5)}(-7)\\\\=-7$

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2(x−3)=(x−1)+7

Oksanka [162]

Answer:

x = 12

(getting to the 20 character limit, please ignore this)

6 0

3 years ago

Read 2 more answers

A random sample of size n1= 25, taken from a normal population with a standard deviation σ1= 5, has a mean X1= 80. A second rand

sesenic [268]

Answer:

The 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

Step-by-step explanation:

Previous concepts

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".

$\bar X_1 =80$ represent the sample mean 1

$\bar X_2 =75$ represent the sample mean 2

n1=25 represent the sample 1 size

n2=36 represent the sample 2 size

$\sigma_1 =5$ sample standard deviation for sample 1

$\sigma_2 =3$ sample standard deviation for sample 2

$\mu_1 -\mu_2$ parameter of interest.

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

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

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

$\bar X_1 -\bar X_2 =80-75=5$

Since the Confidence is 0.94 or 94%, the value of $\alpha=0.06$ and $\alpha/2 =0.03$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.03,0,1)".And we see that $z_{\alpha/2}=1.88$

The standard error is given by the following formula:

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

And replacing we have:

$SE=\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=1.118$

Confidence interval

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

$5-1.88\sqrt{\frac{5^2}{25}+\frac{3^2}{36}}=2.898$

$5+1.8\sqrt{\frac{6^2}{36}+\frac{7^}{49}}=7.102$

So on this case the 94% confidence interval would be given by $2.898 \leq \mu_1 -\mu_2 \leq 7.102$

7 0

3 years ago

The mean amount purchased by a typical customer at Churchill’s Grocery Store is $23.50, with a standard deviation of $5.00. Assu

m_a_m_a [10]

Answer: 0.0170

Step-by-step explanation:

Given : The mean amount purchased by a typical customer at Churchill’s Grocery Store is $23.50, with a standard deviation of $5.00.

i.e. $\mu=23.50$

$\sigma=5$

We assume the distribution of amounts purchased follows the normal distribution.

Sample size : n=50

Let $\overline{x}$ be the sample mean.

Formula : $z=\dfrac{\overline{x}-\mu}{\dfrac{\sigma}{\sqrt{n}}}$

Then, the probability that the sample mean is at least $25.00 will be :-

$P(\overline{x}\geq\25.00)=P(\dfrac{\overline{x}-\mu}{\dfrac{\sigma}{\sqrt{n}}}\geq\dfrac{25-23.50}{\dfrac{5}{\sqrt{50}}})\\\\=P(z\geq2.12)\\\\=1-P(z$

Hence, the likelihood the sample mean is at least $25.00= 0.0170

5 0

4 years ago

I need help with this homework assignment, NO, I am not looking for answers, just help. Here it is.

shusha [124]

Surprisingly, a one-step equation <em>is </em>that simple; it's just an equation that takes one step to solve. So yes, 3 + 4 = 7 would be one you could do. You could also do a simple multiplication or division problem if you'd like, for instance you could do 4*3=12, or 12/4=3. Hope I helped!

4 0

4 years ago

Jenna saves $5 each week. She wants to know how much money she has saved after 6 weeks. How can you represent this? Choose all t

alisha [4.7K]

Answer:

$30

Step-by-step explanation:

5 x 6 = 30

hope this helped :)

6 0

3 years ago