PLEASE HELP

A certain test preparation course is designed to help students improve their scores on the LSAT exam. A mock exam is given at th

Valentin [98]

Answer:

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

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

The mean calculated for this case is $\bar X=12.8$

The sample deviation calculated $s=4.324 \approx 4.3$

$12.8-4.604\frac{4.324}{\sqrt{5}}=3.896$

$12.8+ 4.604\frac{4.324}{\sqrt{5}}=21.704$

So on this case the 99% confidence interval would be given by (3.896;21.704)

Step-by-step explanation:

Data: 10,9,20,13,12

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".

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

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n 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 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 $\bar X=12.8$

The sample deviation calculated $s=4.324$

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=5-1=4$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.005,4)".And we see that $t_{\alpha/2}=4.604$

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

$12.8-4.604\frac{4.324}{\sqrt{5}}=3.896$

$12.8+ 4.604\frac{4.324}{\sqrt{5}}=21.704$

So on this case the 99% confidence interval would be given by (3.896;21.704)

6 0

3 years ago

30 tens =___ 100 <br> 30 ten's is equal to how many 100's

VashaNatasha [74]

Answer:

3

Step-by-step explanation:

30 tens is basically 30 x 10 = 300

300/100 = 3

you get 3 hundreds from 30 tens

3 0

3 years ago

jamil has 3 pet lizards. the pet store owner said that jamil will need to buy a total of 36 crickets to feed his lizards if each

zhenek [66]

In order to do this, we need to look at the info.
Here is what we know:
Each lizard eats the same amount.
They need to buy 36 crickets.
There are three lizards.
What we need to know:
How many crickets does each lizard eat?
How to solve:
Divide 36 by three.
Math:
36/3 = 12.
Final answer:
Each lizard eats 12 crickets.

8 0

4 years ago

Read 2 more answers

Courtney receives a mailer to a local store. In the mailer, there are two coupons which cannot be combined. One coupon is for $2

STatiana [176]

Answer:

B, Courtney should use the 15% off coupon

8 0

3 years ago

Read 2 more answers

A salesperson receives a 2.5% commission on sales, what commission does the salesperson receive for $8,000 in sales

Tcecarenko [31]

Percentage of commission received by the salesperson = 2.5%
Amount of sales made by the salesperson = $8000
Then
The amount of commission received by the salesperson = (2.5/100) * 8000 dollars
= 2.5 * 80 dollars
= 200 dollars
So the salesperson receives a commission of $200 on the total sales made. I hope the procedure is clear enough for you to understand. You can use this method in future for solving similar problems without requiring any help from outside.

7 0

3 years ago