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4 years ago

PLEASE HELP ASAP!!!!!!!!

Mathematics

1 answer:

Marat540 [252]4 years ago

6 0

Answer: If there are 3000 students at Pikeville College, then there should be 150 teachers.

3000/20=150

So there are 150 teachers if there are 3000 students.

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PLEASE HELP I NEED TO GET THIS DONE ASAP !!!!!

Rzqust [24]

Answer:

50.27 cm²

Step-by-step explanation:

Shaded area is the difference in the areas of big and small circles.

Circle area formula: A = πr²
A = π(5²) - π(3²) = π(25 - 9) = 16 π = 50.2654824574 ≈ 50.27cm²

8 0

3 years ago

Read 2 more answers

Mr. Smith goes to the concession stand and buys 2 soft pretzels and 1 cheeseburger for $8.25. Mr. Martin goes to the same conces

polet [3.4K]

Answer:

$4.15

Step-by-step explanation:

Let the cost of a cheeseburger be x

Let the cost of a soft pretzels be y

If Mr. Smith goes to the concession stand and buys 2 soft pretzels and 1 cheeseburger for $8.25, this is expressed as;

x + 2y = 8.25 .... 1

Also, if Mr. Martin goes to the same concession stand and buys 1 soft pretzel and 3 cheeseburgers for $13.50, this is expressed as;

3x + y = 13. 50..... 2

The required equations are:

x + 2y = 8.25

3x + y = 13. 50

Find x and y by solving simultaneously:

From 1: x + 2y = 8.25

x = 8.25 - 2y ..... 3

Substitute 3 into 2

3(8.25-2y)+y = 13.50

24.75 - 6y+y = 13.50

24.75 - 5y = 13.50

-5y = 14.50 - 24.75

-5 y = 10.25

y = -10.25/-5

y = 2.05

Since x = 8.25 - 2y

x = 8.25 - 2(2.05)

x = 8.25 - 4.1

x = 4.15

Hence the cost of a cheesburger is $4.15

4 0

3 years ago

An investigator compares the durability of two different compounds used in the manufacture of a certain automobile brake lining.

strojnjashka [21]

Answer:

1. The 90% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2 is (-2411.84, -1332.16).

2. The point estimate for the true difference between the population means is of -1872.

Step-by-step explanation:

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

Subtraction of Normal Variables:

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

A sample of 212 brakes using Compound 1 yields an average brake life of 47,895 miles. The population standard deviation for Compound 1 is 1590 miles.

This means that $\mu_1 = 47895, \sigma_1 = 1590, n = 212, s_1 = \frac{1590}{\sqrt{212}} = 109.2$

A sample of 180 brakes using Compound 2 yields an average brake life of 49,767 miles. The population standard deviation for Compound 2 is 4152 miles.

This means that $\mu_2 = 49767, \sigma_2 = 4152, n = 180, s_2 = \frac{4152}{\sqrt{180}} = 309.47$

True difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2.

This is the distribution 1 - 2. So

$\mu = \mu_1 - \mu_2 = 47895 - 49767 = -1872$

This is also the point estimate for the true difference between the population means, which is question 2.

$s = \sqrt{s_1^2+s_2^2} = \sqrt{109.2^2+309.47^2} = 328.17$

90% confidence interval

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

$\alpha = \frac{1 - 0.9}{2} = 0.05$

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 $1 - 0.05 = 0.95$ , so Z = 1.645.

Now, find the margin of error M as such

$M = zs = 1.645*328.17 = 539.84$

The lower end of the interval is the sample mean subtracted by M. So it is -1872 - 539.84 = -2411.84

The upper end of the interval is the sample mean added to M. So it is -1872 + 539.84 = -1332.16.

The 90% confidence interval for the true difference between average lifetimes for brakes using Compound 1 and brakes using Compound 2 is (-2411.84, -1332.16).

5 0

3 years ago

According to a survey of workers, StartFraction 2 Over 50 EndFraction of them walk to work, StartFraction 1 Over 50 EndFractio

jenyasd209 [6]

Answer: 6%

Step-by-step explanation:

2/50 walk, that's the same as 4/100 or 4%

1/50 bike, that's the same as 2/100 or 2%

4/100 + 2/100 = 6/100 or 6%

7 0

4 years ago

Brighton is 15 kilometers due east of kinsburg and 13 kilometers due west of Hamilton how many meters apart are kings burg and H

Alborosie

Answer:

ig the answer is 195 kilometers apart from each other cuz 15x13=195

6 0

3 years ago