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3 years ago

-13x=90-2y -6x=48-2y

Mathematics

1 answer:

Kisachek [45]3 years ago

3 0

While it's pretty obvious to most of us that

-13x=90-2y

-6x=48-2y

is a system of linear equations, it'd be well to include that info plus the instructions "solve this system of linear equations."

Subtract the 2nd equation from the first:

-13x=90-2y

+6x=-48+2y

-----------------------

-7x = 42. Then x = -42/7, or x = 6.

Now subst. 6 for x in either one of the given equations. Suppose we use the 2nd equation:

-6x=48-2y

Then -6(6)=48-2y, or -36 = 48 - 2y, or 2y = 48+ 36 = 84. Then y = 42.

The solution is (6, 42).

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Answer:

A ; 23rd century

Step-by-step explanation:

Here, we want to select which of the options is next to have a descending year.

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What we need to work on is the last three digits;

We can have 2210, we can have 2321, we can have 2432, we can also have 2543 and so on.

The most recent of all these is the year 2210, so what century does this belong?

Kindly note that, the years 2001-2100 belong to the 21st century.

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Answer:

1) p1=0.83

2) p2=0.81

3) Option B

4) p=0.82

5) s=0.03

6) z=0.67

7) P=0.50

8) Do not reject H0

Step-by-step explanation:

1) The proportion of Republicans who think the full-body scans should be applied in airports is equal to the ratio between the republicans that think it should over the total Republicans in the poll:

$p=X/n=258/311=0.83$

2) The proportion of Democrats who think the full-body scans should be applied in airports is equal to:

$p=X/n=294/363=0.81$

3) As we want to know if there is a difference in the proportions calculated, not if one is higher or lower than the other, the correct option is B:

$H_0:p_1-p_2=0\\\\H_a:p_1-p_2\neq0$

4) The pooled estimate of a proportion is the average of both proportions:

$\bar{p}=\frac{p_1+p_2}{2}= \frac{0.83+0.81}{2}=0.82$

5) The standard error can be calculated as:

$s=\sqrt{\frac{\bar{p}(1-\bar{p})}{n_1} +\frac{\bar{p}(1-\bar{p})}{n_2}} \\\\s=\sqrt{\frac{0.82*0.18}{311} +\frac{0.82*0.18}{363}} \\\\s=\sqrt{0.00047+0.00041} =\sqrt{0.00088}=0.03$

6) The z-statistic can be calculated as:

$z=\frac{p_1-p_2}{s}=\frac{0.83-0.81}{0.03}=\frac{0.02}{0.03}=0.67$

7) The P-value for z=0.67 is P=0.50 (from the standard normal distribution table).

$2P(Z>|z|)=0.50286$

8) If the significance level is 0.01, the P-value is bigger than the significance level. The effect is not significanct. The null hypothesis is not rejected.

There is not enough evidence to say that both proportions are different.

A. Do not reject H0

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3 years ago