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Keith_Richards [23]
2 years ago
13

Which method is the best way to solve the system shown below? 3x + 4y = 12 3x - 4y = 5

Mathematics
1 answer:
densk [106]2 years ago
3 0

Answer:

3x + 4y = 12 \\ 3x - 4y = 5 \\ 6x = 17 \\ x =  \frac{17}{6}  \\ 3 \times   \frac{17}{5}  - 4y = 5  \\ 51 \div 5 - 4y = 5 \\  \\ 10.2 - 5 = 4y \\ y =  \frac{5.2}{4}

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Which of the following has a slope of –2 and a y-intercept of 4?
Mumz [18]
The coefficient of x is the value for slope in y-intercept form, and the number that we add or subtract is our y-intercept. So in this case, we want to look for a "-2" in front of x and a +4 in the equation. 
Answer choice A fulfills those conditions. (I am also assuming that answer choice A should have had an x in it, but you accidentally forgot to type it.)

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6 0
2 years ago
Find the surface area of the prism. 4 cm 3 cm 5 cm 9 cm
iren [92.7K]

Answer:

540cm^3

Step-by-step explanation:

4*3*5*9=12*5*9=60*9=540

8 0
3 years ago
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What is the answer for -3-(a-2)=7a+15
ale4655 [162]

Answer:

-5.25

Step-by-step explanation:

-3(-a+2)=7a+15

=>3a-6=7a+15

=>-15-6=7a-3a

=>-21=4a

=>a=-21/4=-5.25

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7 0
3 years ago
Refer to the following scenario:You want to see if there is a difference between the exercise habits of Science majors and Math
bekas [8.4K]

Answer:

1. H0: P1 = P2

2. Ha: P1 ≠ P2

3. pooled proportion p = 0.542

4. P-value = 0.0171

5. The null hypothesis failed to be rejected.

At a signficance level of 0.01, there is not enough evidence to support the claim that there is significant difference between the exercise habits of Science majors and Math majors .

6. The 99% confidence interval for the difference between proportions is (-0.012, 0.335).

Step-by-step explanation:

We should perform a hypothesis test on the difference of proportions.

As we want to test if there is significant difference, the hypothesis are:

Null hypothesis: there is no significant difference between the proportions (p1-p2 = 0).

Alternative hypothesis: there is significant difference between the proportions (p1-p2 ≠ 0).

The sample 1 (science), of size n1=135 has a proportion of p1=0.607.

p_1=X_1/n_1=82/135=0.607

The sample 2 (math), of size n2=92 has a proportion of p2=0.446.

p_2=X_2/n_2=41/92=0.446

The difference between proportions is (p1-p2)=0.162.

p_d=p_1-p_2=0.607-0.446=0.162

The pooled proportion, needed to calculate the standard error, is:

p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{82+41}{135+92}=\dfrac{123}{227}=0.542

The estimated standard error of the difference between means is computed using the formula:

s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.542*0.458}{135}+\dfrac{0.542*0.458}{92}}\\\\\\s_{p1-p2}=\sqrt{0.001839+0.002698}=\sqrt{0.004537}=0.067

Then, we can calculate the z-statistic as:

z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{0.162-0}{0.067}=\dfrac{0.162}{0.067}=2.4014

This test is a two-tailed test, so the P-value for this test is calculated as (using a z-table):

\text{P-value}=2\cdot P(z>2.4014)=0.0171

As the P-value (0.0171) is bigger than the significance level (0.01), the effect is not significant.

The null hypothesis failed to be rejected.

At a signficance level of 0.01, there is not enough evidence to support the claim that there is significant difference between the exercise habits of Science majors and Math majors .

We want to calculate the bounds of a 99% confidence interval of the difference between proportions.

For a 99% CI, the critical value for z is z=2.576.

The margin of error is:

MOE=z \cdot s_{p1-p2}=2.576\cdot 0.067=0.1735

Then, the lower and upper bounds of the confidence interval are:

LL=(p_1-p_2)-z\cdot s_{p1-p2} = 0.162-0.1735=-0.012\\\\UL=(p_1-p_2)+z\cdot s_{p1-p2}= 0.162+0.1735=0.335

The 99% confidence interval for the difference between proportions is (-0.012, 0.335).

6 0
3 years ago
What are the solutions of 3x+9+4x+x=
mart [117]

Answer:

3x + 9 + 4x + x = 8x + 9

Step-by-step explanation:

combine like terms

5 0
3 years ago
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