Find the exact value with work problem :S

A simple random sample of 125 SAT scores has a mean of 1522. Assume that SAT scores have a population standard deviation of 335.

Fed [463]

Answer:

$1463.3\:$

Step-by-step explanation:

Since the population standard deviation $\sigma$ , is known, we use the z confidence interval for the mean.

This is given by:

$\bar X-z_{\frac{\alpha}{2} }(\frac{\sigma}{\sqrt{n} } )\:$

For a 95% confidence interval we use $z=1.96$ .

It was also given that: $n=125$ , $\bar X=1522$ and $\sigma=335$

Let us substitute the values to get:

$1522-1.96(\frac{335}{\sqrt{125} } )\:$

$1463.3\:$

<u>Interpretation:</u>

We can say with 95% confidence that the interval between 1463.3 and 1580.7 SAT scores contains the population mean based on the sample 125 SAT scores.

7 0

3 years ago

Find the value power of 3^4

Anastaziya [24]

81, hope this helps

7 0

3 years ago

Read 2 more answers

Nisha and Marcie Drive 20 miles from sisters to hoodoo to go skiing. The speed limit is 75 555 miles per hour. It snowed all nig

slamgirl [31]

If you meant to write this;Nisha and Marcie Drive 20 miles from their sisters to hoodoo to go skiing. The speed limit is 55 miles per hour. It snowed all night, and the safe speed to drive is 40 miles per hour. Explain how you can determine how many more minutes it takes to drive 20 miles at 40 miles per hour in a 55 miles per hour zone.
If you drive 20 miles at 40 mile per hour, then 20 miles divided by 40 miles equals .5.5 times 60 minutes (one hour) is 30 minutesIf you drive 20 miles at 55 mile per hour, then 20 miles divided by 55 miles equals .3636.3636 time 60 minutes (one hour) is 21.8 minutes30 minutes at 40 mph minus 21.8 minutes at 55 mph is 8.2 minutes faster

8 0

4 years ago

A boy had 72 coins and lost 25% of them How muy coins<br> did he have left?

postnew [5]

Answer:

54 coins left

Step-by-step explanation:

72 x .25 = 18

72 - 18 = 54

8 0

3 years ago

Read 2 more answers

If you were asked to convert 75 m/s to km/hr, which conversation factors would you need to use. Select all that apply.

Vilka [71]

Answer:

You need to use A, B, and C.

Step-by-step explanation:

Let's treat the units as variables. I'll illustrate why in a moment.

$75 m/s =\frac{75m}{1s} \\\\\frac{75m}{1s}*\frac{1km}{1000m}=\frac{75m*km}{1000m*s}\\\\\frac{75m*km}{1000m*s}*\frac{60s}{1min}=\frac{(75*60)m*km*s}{1000m*s*min}\\\\\frac{4500m*km*s}{1000m*s*min}*\frac{60min}{1h}=\frac{4500m*km*s*min}{1000m*s*min*h}$

Now, as you can see, we have a giant mess of units to deal with. This is where we can treat the units like separate variables and use a bit of algebra to make our lives easier:

$\frac{4500m*km*s*min}{1000m*s*min*h}=\frac{4500}{1000}*\frac{m*km*s*min}{m*s*min*h}\\\\\frac{4500}{1000}*\frac{m*km*s*min}{m*s*min*h}=\frac{4500}{1000}*\frac{m}{m}*\frac{km}{1}*\frac{s}{s}*\frac{min}{min}*\frac{1}{h}\\\\\frac{4500}{1000}*\frac{m}{m}*\frac{km}{1}*\frac{s}{s}*\frac{min}{min}*\frac{1}{h}=\frac{4500}{1000}*\frac{m*km*s*min}{m*s*min*h}=\frac{4500}{1000}*1*\frac{km}{1}*1*1*\frac{1}{h}\\\\\frac{4500}{1000}*1*\frac{km}{1}*1*1*\frac{1}{h}=\frac{4500}{1000}*\frac{km}{h}\\$

$\frac{4500}{1000}*\frac{km}{h}=\frac{45}{1}*\frac{km}{h}=45 \frac{km}{h}$

So, backtracking through that entire mess, we had to use $\frac{1km}{1000m} ,\frac{60s}{1min} ,\frac{60min}{1h}$ .

These correspond to the options of A, C, and B accordingly.

So you need to use A, B, and C.

8 0

3 years ago