All categories

3 years ago

If the mean, median, and mode are all the same for 4, 9, 7, 8, and x, what is the value of x?

Mathematics

1 answer:

seropon [69]3 years ago

8 0

<h3>Answer: x = 7</h3>

===========================================================

Explanation:

Since we have an odd number of values, this tells us that the median is part of the data set. It's the middle most item after we sort the values.

Recall that the mode is the most frequent item. Since the mode and median are the same, this must mean x can only be equal to one of the following

4, 9, 7 or 8

We can only pick one of those values.

----------------------

If x = 4, then the set {4,9,7,8,x} updates to {4,9,7,8,4} which sorts to {4,4,7,8,9}

The middle most item is in slot 3, which would be 7. So the median is 7.

The median 7 does not match with the mode 4.

So we cross x = 4 off the list.

-----------------------

If x = 7, then we have {4,7,7,8,9}

The mode is 7 and the median is 7. So far, so good.

Now let's compute the mean. Add up the values and divide by 5 because there are 5 items.

(4+7+7+8+9)/5 = 35/5 = 7

We've shown that the set {4,7,7,8,9} has mean 7.

Overall, that set has the same mean, median and mode. So the answer is confirmed.

I'll let you check the cases when x = 8 and x = 9.

You might be interested in

The difference of a number and 6 is -11. What is the number?

Citrus2011 [14]

Answer:

The number is 17

Step-by-step explanation:

8 0

3 years ago

Read 2 more answers

Only false statements have counterexamples. true or false

ycow [4]

I think it is false, because you can have a contradicting statement to a true statement

5 0

3 years ago

HELLLLPPPP PLZZZZZ I WILL MARK BRAINLEIST

NISA [10]

Answer:

Step-by-step explanation:

distance=2436-(-1020)=2436+1020=3456 ft

in two turns points=3-4=-1

in 6 turns=-1/2×6=-3 points

-23+40=17

she had 17 dollars balance.

4 0

3 years ago

Read 2 more answers

Solve the system of linear equations by elimination.<br> -3.x – 5y = -7<br> -4x + 5y = 14

julia-pushkina [17]

Answer:

(- 1, 2 )

Step-by-step explanation:

Given the 2 equations

- 3x - 5y = - 7 → (1)

- 4x + 5y = 14 → (2)

Add the 2 equations term by term to eliminate y , that is

- 7x + 0 = 7

- 7x = 7 ( divide both sides by - 7 )

x = - 1

Substitute x = - 1 into either of the 2 equations and solve for y

Substituting into (1)

- 3(- 1) - 5y = - 7

3 - 5y = - 7 ( subtract 3 from both sides )

- 5y = - 10 ( divide both sides by - 5 )

y = 2

solution is (- 1, 2 )

8 0

3 years ago

Read 2 more answers

At Western University the historical mean of scholarship examination scores for freshman applications is 900. A historical popul

vampirchik [111]

Answer:

a) Null Hypothesis: $\mu =900$

Alternative hypothesis: $\mu \neq 900$

b) The 95% confidence interval would be given by (910.05;959.95)

c) Since we confidence interval not ocntains the value of 900 we fail to reject the null hypothesis that the true mean is 900.

d) $z=\frac{935 -900}{\frac{180}{\sqrt{200}}}=2.750$

Since is a bilateral test the p value is given by:

$p_v =2*P(Z>2.750)=0.0059$

Step-by-step explanation:

a. State the hypotheses.

On this case we want to check the following system of hypothesis:

Null Hypothesis: $\mu =900$

Alternative hypothesis: $\mu \neq 900$

b. What is the 95% confidence interval estimate of the population mean examination score if a sample of 200 applications provided a sample mean x¯¯¯= 935?

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".

$\bar X=935$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

$\sigma=180$ represent the population standard deviation

n=200 represent the sample size

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

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

In order to calculate the mean and the sample deviation we can use the following formulas:

$\bar X= \sum_{i=1}^n \frac{x_i}{n}$ (2)

$s=\sqrt{\frac{\sum_{i=1}^n (x_i-\bar X)}{n-1}}$ (3)

The mean calculated for this case is $\bar X=3278.222$

The sample deviation calculated $s=97.054$

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: "=-NORM.INV(0.025,0,1)".And we see that $z_{\alpha/2}=1.96$

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

$935-1.96\frac{180}{\sqrt{200}}=910.05$

$935+1.96\frac{180}{\sqrt{200}}=959.95$

So on this case the 95% confidence interval would be given by (910.05;959.95)

c. Use the confidence interval to conduct a hypothesis test. Using α= .05, what is your conclusion?

Since we confidence interval not ocntains the value of 900 we fail to reject the null hypothesis that the true mean is 900.

d. What is the p-value?

The statistic is given by:

$z=\frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n}}}$

If we replace we got:

$z=\frac{935 -900}{\frac{180}{\sqrt{200}}}=2.750$

Since is a bilateral test the p value is given by:

$p_v =2*P(Z>2.750)=0.0059$

So then since the p value is less than the significance we can reject the null hypothesis at 5% of significance.

8 0

3 years ago

If the mean, median, and mode are all the same for 4, 9, 7, 8, and x, what is the value of x?​

If the mean, median, and mode are all the same for 4, 9, 7, 8, and x, what is the value of x?