Use front-end estimation to add 495 + 650 + 875. Indicate the three digits that you will add first?

What is thei value of their given digits the 4 in 440

Sedaia [141]

The first 4 on the left has a value of 400. The next 4 has a value of 40. The first 4 is in the hundreds place and the second 4 is in the 10's place.

4 0

3 years ago

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

you make a necklace using blue, purple and green beads in a ratio of 1:1:2. you use a total of 168 beads. How many green beads a

vesna_86 [32]

The answer is 84 green beads.

To get that you need to do 168 divide by 4 (four because I look at it like this 1:1:2 is like 1:1:1:1) That answer is 4 then double that and you get 84.

3 0

3 years ago

Read 2 more answers

A line through the origin has a slope of 1 / 3. Carlos thinks the slope of a perpendicular line at the origin will be 3.

OLEGan [10]

Answer:

Carlos is incorrect.

Step-by-step explanation:

We have been given that a line through the origin has a slope of $\frac{1}{3}$ . Carlos thinks the slope of a perpendicular line at the origin will be 3.