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3 years ago

42 = 4n -7(n-9) solve it

Mathematics

2 answers:

Murljashka [212]3 years ago

4 0

42=4n-7n+63
42=-3n+63
-21=-3n
N=7

Artemon [7]3 years ago

3 0

I hope this helps you

42=4n-7n-7. (-9)

42=-3n+63

-3n=-21

n=7

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Direct mail advertisers send solicitations ("junk mail") to thousands of potential customers in the hope that some will buy the

harina [27]

Answer:

The interval is (.0817, .118).

Step-by-step explanation:

Let's make this interval! The easy way is to go to STAT->TEST->A, 1-prop z-int, but I will show the long way.

1. Conditions

First we must check the conditions.

Randomization condition: The sample is given to be random, so we can assume independence.

Success/failure condition: Both np>10 and nq>10 must be met.

np = 1030(103/1030) = 103 ✓
nq = 1030(927/1030) = 927 ✓

10% condition: The sample cannot be greater than 10% of the population.

10n < N, 10(1030) < 200000 ✓

All conditions are met, so we can use a 1-proportion z-interval to represent the data.

2. Mechanics

Find $\hat{p}$ , the sample proportion.

103/1030 = .1

$\hat{q}$ , then, the probability of not p, is 1 - .1 = .9

Find z* (z star), the critical z-value.

You can do this on your calculator using 2nd->VARS->3 (or you can memorize it - it's 1.96. Winky face.) This is called the invNorm function, that takes the left side area under the normal curve. But what do we plug in to the invNorm function?

invNorm(.975) = 1.96

Plug values into the equation.

$\hat{p}$ ± z* $\sqrt{\frac{\hat{p}\hat{q}}{n} }$

.1 ± 1.96 $\sqrt{\frac{.1*.9}{1030} }$

.1 ± 1.96(.00935)

.1 - .0183 = .0817

.1 + .0183 = .118

(.0817, .118)

3. Conclusion

Based on this sample, we are 95% confident that the proportion of people the company contacts who may buy something is between .0817 and .118. That isn't very likely, but maybe they'll make a little profit!

5 0

3 years ago

The table below shows data from a survey about the amount of time students spend doing homework each week. The students were in

nadezda [96]

Answer:

The correct option is;

Both spreads are best described by the standard deviation

Step-by-step explanation:

The given information are;

, College High School

High, 20 20

Low, 6 3

Q₁, 8 5.5

Q₃, 18 16

IQR, 10 10.5

Median, 14 11

Mean, 13.3 11

σ, 5.2 5.4

Checking for outliers, we have

College

Q₁ - 1.5×IQR gives 8 - 1.5×10 = -7

Q₃ + 1.5×IQR gives 18 + 1.5×10 = 33

For high school

Q₁ - 1.5×IQR gives 5.5 - 1.5×10.5 = -10.25

Q₃ + 1.5×IQR gives 16 + 1.5×10.5 = 31.75

Therefore, there are no outliers and the data is representative of the population

From the data, for the college students, it is observed that the difference between the mean, 13.3 and Q₁, 8, and between Q₃, 18 and the mean,13.3 is approximately the standard deviation, σ, 5.2

The difference between the low and the high is also approximately 3 standard deviations

Therefore the college spread is best described by the standard deviation

Similarly for the high school students, the IQR is approximately two standard deviations, the difference between the mean, 11 and Q₁, 5.5, and between Q₃, 16 and the mean,11 is approximately the standard deviation, σ, 5.4

Therefore the high school spread is also best described by the standard deviation.

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3 years ago

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Vesna [10]

Answer:

your answer is 13.

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3 years ago

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Vitek1552 [10]

The answer is square

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Sindrei [870]

Answer:

D) 42.16

Total: $553.13

Step-by-step explanation:

Multiply the subtotal, 510.97, by 8.25%. To do that just turn the 8.25% into a decimal which is 0.0825. The answer to that would be 42.155025 and rounded it would be 42.16 so the tax would be $42.16.

The total to the entire thing would be $553.13 since you just add the tax and subtotal together.

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3 years ago

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