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2 years ago

Round 78,879 to the nearest ten

Mathematics

2 answers:

yan [13]2 years ago

7 0

Answer:

78,880

Step-by-step explanation:

Add one to 7 and make the 9 behind it 0

Inessa [10]2 years ago

4 0

The answer is 78,880

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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

2 years ago

Can anyone help me with number 3 please

Gnoma [55]

Answer:

I think is (B)

4 0

2 years ago

The results of joes survey show that baseball is the favorite sport for 18 out of 25 people. What percent do not like sports?

charle [14.2K]

well if 18 out of 25 like it, then the remaining 7 doesn't like it, namely 7 out of 25.

if we take 25 to be the 100%, what is 7 off of if in percentage?

$\bf \begin{array}{ccll} amount&\%\\ \cline{1-2} 25&100\\ 7&x \end{array}\implies \cfrac{25}{7}=\cfrac{100}{x}\implies 25x=700\implies x=\cfrac{700}{25}\implies x=28$

7 0

2 years ago

If the probability that your DVD player breaks down before the extended warranty expires is 0.034, what is the probability that

schepotkina [342]

Answer:

0.966

Step-by-step explanation:

Given that:

Probability of DVD player breaking down before the warranty expires = 0.034

To find:

The probability that the player will not break down before the warranty expires = ?

Solution:

Here, The two events are:

1. The DVD player breaks down before the warranty gets expired.

2. The DVD player breaks down after the warranty gets expired

In other words, the 2nd event can be stated as:

The DVD does not break down before the warranty gets expired.

The two events here, have nothing in common i.e. they are mutually exclusive events.

So, Sum of their probabilities will be equal to 1.

$\bold{P(E_1)+P(E_2)=1}\\\Rightarrow 0.034+P(E_2)=1\\\Rightarrow P(E_2)=1-0.034\\\Rightarrow P(E_2)=\bold{0.966}$

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2 years ago

Pleaseeeeeeeee please help me i can’t get anything wrong save me please

Olegator [25]

Im 99.99999% it is the top left

4 0

2 years ago

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