Help with my homework plz I need it

Ahh i hate math fr someone help

Dmitry_Shevchenko [17]

I think C but probably try to find something to back it up
All you gotta do is divide the pound by the cost

6 0

3 years ago

Elimination 4x-7y=5 9x-7y=-15

Afina-wow [57]

Answer:

x = -4

Step-by-step explanation:

To make this easier to explain and easier to solve, we're going to first multiply the second equation of 9x-7y=-15 by -1 to make the y coefficient positive.

This results in -9x+7y=15.

When we line up the two equations on top of each other now, we'll see that both the first and second equations have opposite y coefficients, which is vital for elimination.

The next step is to add the second equation to the first one. Teachers may tell you to subtract, but I find it easier to add if you make the two y coefficients of negative value to each other.

4x-7y=5

+ -9x+7y=15

___________

-5x+0y=20, or just -5x=20, because you have successfully eliminated the y variable.

From there, you're going to solve like a normal equation (divide both sides by -5) toget you x=-4.

7 0

4 years ago

Look at this coordinate plane

11111nata11111 [884]

Answer:

Hrmm

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

Cable Strength: A group of engineers developed a new design for a steel cable. They need to estimate the amount of weight the ca

KatRina [158]

Answer:

95% confidence interval for the mean breaking strength of the new steel cable is [763.65 lb , 772.75 lb].

Step-by-step explanation:

We are given that the engineers take a random sample of 45 cables and apply weights to each of them until they break. The mean breaking weight for the 45 cables is 768.2 lb. The standard deviation of the breaking weight for the sample is 15.1 lb.

Since, in the question it is not specified that how much confidence interval has be constructed; so we assume to be constructing of 95% confidence interval.

Firstly, the Pivotal quantity for 95% confidence interval for the population mean is given by;

P.Q. = $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample mean breaking weight = 768.2 lb

s = sample standard deviation = 15.1 lb

n = sample of cables = 45

$\mu$ = population mean breaking strength

Here for constructing 95% confidence interval we have used One-sample t test statistics as we don't know about population standard deviation.

So, 95% confidence interval for the population mean, $\mu$ is ;

P(-2.02 < $t_4_4$ < 2.02) = 0.95 {As the critical value of t at 44 degree

of freedom are -2.02 & 2.02 with P = 2.5%}

P(-2.02 < $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ < 2.02) = 0.95

P( $-2.02 \times {\frac{s}{\sqrt{n} } }$ < ${\bar X-\mu}$ < $2.02 \times {\frac{s}{\sqrt{n} } }$ ) = 0.95

P( $\bar X-2.02 \times {\frac{s}{\sqrt{n} } }$ < $\mu$ < $\bar X+2.02 \times {\frac{s}{\sqrt{n} } }$ ) = 0.95

95% confidence interval for $\mu$ = [ $\bar X-2.02 \times {\frac{s}{\sqrt{n} } }$ , $\bar X+2.02 \times {\frac{s}{\sqrt{n} } }$ ]

= [ $768.2-2.02 \times {\frac{15.1}{\sqrt{45} } }$ , $768.2+2.02 \times {\frac{15.1}{\sqrt{45} } }$ ]

= [763.65 lb , 772.75 lb]

Therefore, 95% confidence interval for the mean breaking strength of the new steel cable is [763.65 lb , 772.75 lb].

3 0

4 years ago

10 points help plz.

serg [7]

Answer:b

Step-by-step explanation:

8 0

3 years ago

Read 2 more answers