There are 54 students in the cafeteria 30 girl sand 24 boys what is the ratio of girls to boys in cafeteria

Which expression is equivalent to 2(4 + x) + 3 ?

Elden [556K]

The correct answer is A. 2*4+x+3

6 0

2 years ago

Why did many americans seek a change in the election of 1980

Naya [18.7K]

<span>That is because they were unsatisfied with the way Jimmy Carter was running the country. Not only was economy doing fairly poor, but he also lost a lot of support because of the way he solved the hostage crisis. All of these combined to allow Ronald Reagan to easily win the presidency.</span>

5 0

3 years ago

Read 2 more answers

Helplpllplllpllplplplplpp mememememememememe

Ray Of Light [21]

The radius is shown as 5 cm,

Use the given formula:

Using 3.14 for PI:

Volume = 4/3 x 3.14 x 5^3

Volume = 523.33 cubic cm

The question is cut off, so round the answer as needed.

6 0

2 years ago

Read 2 more answers

Solve for x. 0.2x – 1.8 5 = 4.2

spin [16.1K]

Answer:

Step-by-step explanation:

0.2x – 1.8/5 = 4.2

0.2x - 1.8 = 4.2 (5)

x =<u> 21 + 1.8 </u>

0.2

x = 22.8 / 0.2

x = 114

4 0

3 years ago

A study was conducted and two types of engines, A and B, were compared. Fifty experiments were performed using engine A and 75 u

USPshnik [31]

Answer:

a) -6 mpg.

b) 2.77 mpg

c) The 95% confidence interval for the difference of population mean gas mileages for engines A and B and interpret the results, in mpg, is (-8.77, -3.23).

Step-by-step explanation:

To solve this question, we need to understand the central limit theorem, and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem estabilishes 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.

Gas mileage A: Mean 36, standard deviation 6, sample of 50:

So

$\mu_A = 36, s_A = \frac{6}{\sqrt{50}} = 0.8485$

Gas mileage B: Mean 42, standard deviation 8, sample of 50:

So

$\mu_B = 42, s_B = \frac{8}{\sqrt{50}} = 1.1314$

Distribution of the difference:

Mean:

$\mu = \mu_A - \mu_B = 36 - 42 = -6$

Standard error:

$s = \sqrt{s_A^2+s_B^2} = \sqrt{0.8485^2+1.1314^2} = 1.4142$

A. Find the point estimate.

This is the difference of means, that is, -6 mpg.

B. Find the margin of error

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = zs = 1.96*1.4142 = 2.77$

The margin of error is of 2.77 mpg

C. Construct the 95% confidence interval for the difference of population mean gas mileages for engines A and B and interpret the results(5 pts)

The lower end of the interval is the sample mean subtracted by M. So it is -6 - 2.77 = -8.77 mpg

The upper end of the interval is the sample mean added to M. So it is -6 + 2.77 = -3.23 mpg

The 95% confidence interval for the difference of population mean gas mileages for engines A and B and interpret the results, in mpg, is (-8.77, -3.23).

8 0

2 years ago