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2 years ago

Find the values of t for which the rockets height is 50 feet. Round the answers

Mathematics

1 answer:

Svetach [21]2 years ago

7 0

Answer:

t= 0.398 or 126 (to 3sf)

Step-by-step explanation:

When h=50,

126t-t²=50

t²-126t+50=0

t= 0.398 or 126 (to 3sf)

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Carlos runs 7 miles in 57 3/4 mins. how fast did he run each mile?

san4es73 [151]

To find how much minutes Carlos runs each mile, you must first multiply 57.75 by 1 which is 57.75 because 57 3/4 and 57.75 is the same thing. Next, you must divide 57.75 by 7. Therefore, Carlos runs 8.25 minutes a mile.

3 0

3 years ago

In a random sample of 25 people, the mean commute time to work was 33.9 minutes and the standard deviation was 7.2 minutes. Ass

Phoenix [80]

Answer:

$33.9-1.32\frac{7.2}{\sqrt{25}}=31.999$

$33.9+1.32\frac{7.2}{\sqrt{25}}=35.801$

So on this case the 80% confidence interval would be given by (31.999;35.801)

And the margin of error is given by:

$ME = t_{\alpha/2}\frac{s}{\sqrt{n}}$

And replacing we got:

$ME = 1.32\frac{7.2}{\sqrt{25}} =1.9008$

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".

$\bar X=33.9$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s=7.2 represent the sample standard deviation

n=25 represent the sample size

Solution to the problem

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:

$df=n-1=25-1=24$

Since the Confidence is 0.80 or 80%, the value of $\alpha=0.2$ and $\alpha/2 =0.1$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.01,24)".And we see that $t_{\alpha/2}=1.32$

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

$33.9-1.32\frac{7.2}{\sqrt{25}}=31.999$

$33.9+1.32\frac{7.2}{\sqrt{25}}=35.801$

So on this case the 80% confidence interval would be given by (31.999;35.801)

And the margin of error is given by:

$ME = t_{\alpha/2}\frac{s}{\sqrt{n}}$

And replacing we got:

$ME = 1.32\frac{7.2}{\sqrt{25}} =1.9008$

7 0

4 years ago

A cable company offers two movie plans. One plan costs $129 per month plus $5 per movie. The other plan costs $150 per month for

Svetradugi [14.3K]

Answer:
You can’t make it the same, but you can make it almost the same.

Maggie would have to rent 4 movies to make the plans’ cost almost the same.

Explanation:
$150-$129= 21
21 divided by 5= 4.2 (You can’t rent 4.2 movies, so we go with 4)
4x5=20+$129= $149 (Almost $150)

So, Maggie would have to rent 4 movies to make the costs almost the same.

Hope this is helpful!!
P.S Sorry if there was another way to make the costs equal, I’m not the best at math!
:D

4 0

3 years ago

Find the intersection.<br> (5, 7, 9, 10) n (2, 7, 10, 11)

marishachu [46]

Answer:

7, 10

Step-by-step explanation:

7 and 10 appear in each set of numbers

3 0

3 years ago

Help. Your backyard is 10 feet longer than it is wide. Its area is 8624 square feet. Its width is Solve in quadratic equation.

Valentin [98]

Would you say 88in by 98in is correct?

7 0

4 years ago