90 is one tenth of what?

At a large Midwestern university, a simple random sample of 100 entering freshmen in 1993 found that 20 of the sampled freshmen

guajiro [1.7K]

Answer:

The 90% confidence interval for the difference of proportions is (0.01775,0.18225).

Step-by-step explanation:

Before building the confidence interval, we need to understand the central limit theorem and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean $\mu = p$ and standard deviation $s = \sqrt{\frac{p(1-p)}{n}}$

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

p1 -> 1993

20 out of 100, so:

$p_1 = \frac{20}{100} = 0.2$

$s_1 = \sqrt{\frac{0.2*0.8}{100}} = 0.04$

p2 -> 1997

10 out of 100, so:

$p_2 = \frac{10}{100} = 0.1$

$s_2 = \sqrt{\frac{0.1*0.9}{100}} = 0.03$

Distribution of p1 – p2:

$p = p_1 - p_2 = 0.2 - 0.1 = 0.1$

$s = \sqrt{s_1^2+s_2^2} = \sqrt{0.04^2 + 0.03^2} = 0.05$

Confidence interval:

$p \pm zs$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a p-value of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

The lower bound of the interval is:

$p - zs = 0.1 - 1.645*0.05 = 0.01775
$

The upper bound of the interval is:

$p + zs = 0.1 + 1.645*0.05 = 0.18225
$

The 90% confidence interval for the difference of proportions is (0.01775,0.18225).

6 0

3 years ago

Each angle of a regular pentagon has a measure of

Andrew [12]

Answer:

congruent

Step-by-step explanation:

All sides are the same length (congruent) and all interior angles are the same size (congruent). To find the measure of the interior angles, we know that the sum of all the angles is 540 degrees (from above)... And there are five angles... So, the measure of the interior angle of a regular pentagon is 108 degrees.

6 0

4 years ago

I need not just the answer but the work written out

Mekhanik [1.2K]

Answer:

A(3) = -6 + (3 - 1) (5)

-6 + (2)(5)

-6 + (10)

4

A(4) = -6 + (4 - 1) (5)

-6 + (3)(5)

-6 + 15

9

A(10) = -6 + (10 - 1) (5)

-6 + (9)(5)

-6 + 45

39

6 0

3 years ago

34,000 people attended a ballgame at a stadium that offers two kind of seats: general admission and reserved. The day's receipts

hoa [83]

Answer:

The number of people who paid $ 12 for reserved seat is 5,000

The number of people who paid $ 4 for general seat is 29,000

Step-by-step explanation:

Given as :

The total number of people attending a ballgame = 34,000

The total receipt of the ticket's seat = $ 176,000

The amount pad for reserved seat = $ 12

The amount paid for general admission = $ 4

Let The number of people for reserved seat = r

And The number of people for general admission = g

Now, According to question

The total number of people attending a ballgame = The number of people for reserved seat + The number of people for general admission

or, r + g = 34,000 ...........1

The total receipt of the ticket's seat = The amount pad for reserved seat × The number of people for reserved seat + The amount paid for general admission × The number of people for general admission

Or, $ 12 × r + $ ×4 g = $ 176,000 .........2

or, $ 12 × ( r + g ) = $ 12 × 34000

Or, $ 12 r + $ 12 g = $ 408,000

Solving equation

( $ 12 r + $ 12 g ) - ($ 12 r + $ 4 g ) = $ 408,000 - $ 176,000

Or, ( $ 12 r - $ 12 r ) + ( $ 12 g - $ 4 g ) = $ 232,000

Or 0 + 8 g = 232,000

∴ g = $\frac{232000}{8}$

I.e g = 29,000

So , The number of people for general admission = g = 29,000

Put the value of g in Eq 1

I.e r + g = 34,000

or , r = 34,000 - g

∴ r = 34000 - 29000

I.e r = 5,000

So, The number of people for reserved seat = r = 5,000

Hence The number of people who paid $ 12 for reserved seat is 5,000

And The number of people who paid $ 4 for general seat is 29,000 Answer

6 0

3 years ago

The amounts of 8 charitable contributions are $100, $80, $250, $100, $500, $1000, $100, and $150.

cluponka [151]

Due to the fact that mode means most present number your answer would be mode or 100 dollars

5 0

3 years ago