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scoundrel [369]

2 years ago

14

A tax preparation firm is interested in comparing the quality of work at two of its regional offices. the observed frequencies s

howing the number of sampled returns with errors and the number of sampled returns that were correct are as follows.
regional office
return office 1 office 2
error 35 28
correct 217 274

1 answer:

Veronika [31]2 years ago

7 0

The sample proportion of returns with errors at the two tax offices will be 0.1389 and 0.0927 respectively.

<h3>How to calculate the sample proportion?</h3>

From the information, the the observed frequencies showing the number of sampled returns with errors and the number of sampled returns were given.

The sample proportion will be:

P1 = 35/(35 + 217)

= 35/252

= 0.1389

P2 = 28/(28 + 274)

= 28/302

= 0.0927

Learn more about sample proportion on:

brainly.com/question/24232216

#SPJ1

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Find a cubic function f(x) = ax^3 + bx^2 + cx + d that has a local maximum value of 3 at x = −3 and a local minimum value of 0 a

Ahat [919]

Answer:

f(x) = (3x³ + 9x² - 27x + 15)/32

Step-by-step explanation:

f'(x) = 3ax² + 2bx + c

Maximum or minimum: f'(x) = 0

Maximum: f'(-3) = 0 and f(-3) = 3

Minimum: f'(1) = 0 and f(1) = 0

f'(-3) = 0 leads 27a - 6b + c = 0 (1)

f'(1) = 0 leads 3a + 2b + c = 0 (2)

f(-3) = 3 leads -27a + 9b -3c + d = 3 (3)

f(1) = 0 leads a + b + c + d = 0 (4)

(1) - (2): 24a - 8b = 0, or 3a - b = 0, b = 3a

(3) - (4) -28a + 8b - 4c = 3 (5)

(1) * 4 + (5): 80a - 16b = 3,

use b = 3a, get 80a - 16*3a = 3, 32a = 3, a = 3/32, b = 3a = 9/32

From (2): c = -3a - 2b = -9/32 - 18/32 = -27/32

From (4): d = -a - b - c = -3/32 - 9/32 + 27/32 = 15/32

So

f(x) = (3x³ + 9x² - 27x + 15)/32

3 0

2 years ago

Researchers at the National Cancer Institute released the results of a study that investigated the effect of weed-killing herbic

jolli1 [7]

Answer:

The 95% confidence interval for the difference in the proportion of cancer diagnoses between the two groups is (0.3834, 0.5166).

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.

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.

The randomly sampled 400 dogs from homes where an herbicide was used on a regular basis, diagnosing lymphoma in 230 of them.

This means that:

$p_h = \frac{230}{400} = 0.575, s_h = \sqrt{\frac{0.575*0.425}{400}} = 0.0247$

Of 200 dogs randomly sampled from homes where no herbicides were used, only 25 were found to have lymphoma.

This means that:

$p_n = \frac{25}{200} = 0.125, s_n = \sqrt{\frac{0.125*0.875}{200}} = 0.0234$

Distribution of the difference:

$p = p_h - p_n = 0.575 - 0.125 = 0.45$

$s = \sqrt{s_h^2+s_n^2} = \sqrt{0.0247^2 + 0.0234^2} = 0.034$

Confidence interval:

The confidence interval is:

$p \pm zs$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

95% confidence level

So $\alpha = 0.05$ , z is the value of Z that has a pvalue of $1 - \frac{0.05}{2} = 0.975$ , so $Z = 1.96$ .

The lower bound is $0.45 - 1.96(0.034) = 0.3834$

The upper bound is $0.45 + 1.96(0.034) = 0.5166$

The 95% confidence interval for the difference in the proportion of cancer diagnoses between the two groups is (0.3834, 0.5166).

3 0

3 years ago

if there are two containers of sugar solution, the first is 4% concentration and second is 8% concentration. how much of each sh

Elina [12.6K]

Answer:

<u>30 gallons solution 4% and 10 gallons solution 8%</u>

Step-by-step explanation:

<h3>x•4%+y•8%=40•5% </h3>

<em><u>4x+8y=40•5 and x+y=40</u></em>

x=40-y

4(40-y)+8y=200

160-4y+8y=200

4y=200-160

4y=40 => y=10 (gallons solution 8%)

=> x=40-10=30 (gallons solution 4%)

30 gallons solution 4% and 10 gallons solution 8%

5 0

3 years ago

How can I solve this.. Need asap.. Please and thankyou❤️❤️

Elena L [17]

Divide 1500 by 5 to get one fifth of the savings. Multiply that by 12 to get yearly savings. You end up with 3600.

8 0

3 years ago

The surface areas of two similar solids are 340 yd² and 1,158 yd². The volume of the larger solid is 1,712 yd³. What is the volu

ratelena [41]

The ratio of surface area is equal to the ratio of the square of the corresponding dimensions. And ratio of volumes of two solids is equal to the cube of the ratio of the corresponding dimensions .

We start with the relation between ratio of surface area and ratio of corresponding sides. That is

$\frac{340}{1158}=(\frac{x}{y} )^2$

Here x and y are the corresponding sides .

$\frac{x}{y} =\sqrt{\frac{340}{1158} } =0.542$

Let the volume of the smaller one be v

$\frac{v}{1712}=0.542^3$

$v=1712*0.542^3=272$

So for the smaller solid, volume is 272 . And the correct option is the first option .

4 0

3 years ago