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Andrews [41]
3 years ago
10

Find the sum and choose the correct answer.

Mathematics
2 answers:
MrRa [10]3 years ago
8 0
Hi

2n³ + 4n² - 7 + (-n³ - 8n - 2) = 2n³ - n³ + 4n² - 8n - 7 - 2 

n³ + 4n² - 8n - 9

Answer: n³ + 4n² - 8n - 9
Vaselesa [24]3 years ago
7 0

Answer:

Correct answer is:

n³+4n²-8n-9

Step-by-step explanation:

We have to find the sum of:

2n³ + 4n² - 7  and  -n³ - 8n - 2

On adding both terms:

2n³ + 4n² - 7 + (-n³ - 8n - 2)

= 2n³ - n³ + 4n² - 8n - 7 - 2

= n³+4n²-8n-9

Hence, sum of 2n³ + 4n² - 7  and  -n³ - 8n - 2 is:

n³+4n²-8n-9

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Mario is paid a salary of $500 plus 8% of sales. Calculate his total income if his sales total $10,890 in the
Gre4nikov [31]

Answer:

His total income is of $1,371.2.

Step-by-step explanation:

His salary is of $500, plus 8% of his sales.

In this question:

Sales of $10,890. So his salary is given by:

S = 500 + 0.08*10890 = 500 + 871.2 = 1371.2

His total income is of $1,371.2.

7 0
2 years ago
The average annual cost (including tuition, room, board, books and fees) to attend a public college takes nearly a third of the
Crazy boy [7]

Answer:

a) Private Colleges

Sample mean = 42.5 thousand dollars

Standard deviation = S1 = 6.62 thousand dollars.

Public colleges

Sample mean = 22.3 thousand dollars

Standard deviation = 4.34 thousand dollars

b) The difference in sample mean for both cases = 42.5 - 22.3 = 20.2 thousand dollars

The average amount of going to a Private college is 20.2 thousand dollars more than the average cost of going to public colleges

c) 95% confidence interval for a sampling distribution of the difference of the cost of private and public colleges is given as

(15.0, 25.4) thousand dollars.

Step-by-step explanation:

Private colleges.

52.8 43.2 45.0 33.3 44.0 30.6 45.8 37.8 50.5 42.0

Public colleges.

20.3 22.0 28.2 15.6 24.1 28.5 22.8 25.8 18.5 25.6 14.4 21.8

a) Calculate sample mean and standard deviation for both data set.

Mean = (Σx)/N

where N = Sample size

Σx = sum of all variables

Private colleges

Σx = (52.8+43.2+45.0+33.3+44.0+30.6+45.8+37.8+50.5+42.0) = 425

N = 10

Mean = 425/10 = 42.5 thousand dollars

Standard deviation = S1 = √[Σ(x - xbar)²/N]

Σ(x - xbar)² = (52.8-42.5)² + (43.2-42.5)²

+ (45.0-42.5)² + (33.3-42.5)²

+ (44.0-42.5)² + (30.6-42.5)² + (45.8-42.5)² + (37.8-42.5)² + (50.5-42.5)² + (42.0-42.5)² = 438.56

N = 10

Standard deviation = √[Σ(x - xbar)²/N]

Standard deviation = √(438.56/10) = 6.62 thousand dollars

Public colleges

Mean = (Σx)/N

Σx =

(20.3+22.0+28.2+15.6+24.1+28.5+22.8+25.8+18.5+25.6+14.4+21.8) = 267.6

N = 12

Mean = (267.6/12) = 22.3 thousand dollars

Standard deviation = √[Σ(x - xbar)²/N]

[Σ(x - xbar)²

(20.3-22.3)² + (22.0-22.3)² + (28.2-22.3)² + (15.6-22.3)² + (24.1-22.3)² + (28.5-22.3)² + (22.8-22.3)² + (25.8-22.3)² + (18.5- 22.3)² + (25.6-22.3)² +(14.4-22.3)+(21.8-22.3) = 225.96

N = 12

standard deviation = s2 = √(225.96/12) = 4.34 thousand dollars

b) The difference in sample mean for both cases = 42.5 - 22.3 = 20.2 thousand dollars

The average amount of going to a Private college is 20.2 thousand dollars more than the average cost of going to public colleges.

c. Develop a 95% confidence interval of the difference between the annual cost of attending private and pubic colleges.

95% confidence interval, private colleges have a population mean annual cost $ to $ more expensive than public colleges.

To combine the distribution in this manner,

Sample mean of difference = 20.2 thousand dollars

Combined standard deviation of the sampling distribution = √[(S1²/n1) + (S2²/n2)]

= √[(6.62²/10) + (4.34²/12)] = 2.44 thousand dollars

Confidence interval = (Sample mean) ± (Margin of error)

Sample mean = 20.2

Margin of error = (critical value) × (standard deviation of the sampling distribution)

standard deviation of the sampling distribution = 2.44

To obtain the critical value, we need the t-score at a significance level of 5%; α/2 = 0.025

we obtain the degree of freedom too

The degree of freedom, df, is calculated in the attached image.

df = 15

t (0.025, 15) = 2.13145 from the tables

Margin of error = 2.13145 × 2.44 = 5.20

Confidence interval = (Sample mean) ± (Margin of error)

= (20.2 ± 5.2) = (15.0, 25.4)

Hope this Helps!!!

8 0
3 years ago
Joan makes a base salary of $275 per week and a commission of 4% of sales over $1000. If she sells $1250 of merchandise this wee
Lerok [7]

Joan makes $275/week.

In addition to $275, she also makes 4 percent on sales over $1000.

So, 1250 - 1000 = 250.

Then 250(0.04) = 10.

Let t = amount of her paycheck for the week.

t = $275 + $10

t = $285

8 0
3 years ago
In how many ways can 3person study groups beselected from a class of 25students?Note: nrn!r!(n-r)!nEnter
nlexa [21]

Answer:

2,300

Explanation:

This is given as:

\begin{gathered} 25\text{ combination 3 represented as:} \\ ^nC_r=\frac{n!}{r!(n-r)!} \\ n=25 \\ r=3 \\ ^{25}C_3=\frac{25!}{3!(25-3)!} \\ ^{25}C_3=\frac{25\times24\times23\times22!}{3!\times22!} \\ ^{25}C_3=\frac{25\times24\times23}{3\times2\times1} \\ ^{25}C_3=2300 \end{gathered}

Therefore, there are 2,300 ways that 3 persons can be selected from 25 people

8 0
1 year ago
A school  surveys 100 students to find out their favorite football team.  Seventy - one of the students said the Dallas Cowboys.
almond37 [142]
So out of 100 questioned 71 said Dallas Cowboys , that means 71% did  , now we have to work out 71% of 1200 which is 852 
3 0
3 years ago
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