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3 years ago

(a) find parametric equations for the line of intersection of the planes x + y + z = 2 and x + 7y + 7z = 2

1 answer:

3 0

Direction vector of line of intersection of two planes is the cross product of the normal vectors of the planes, namely
p1: x+y+z=2
p2: x+7y+7z=2

and the corresponding normal vectors are: (equiv. to coeff. of the plane)
n1:<1,1,1>
n2:<1,7,7>

The cross product n1 x n2
vl=
i j l
1 1 1
1 7 7
=<7-7, 1-7, 7-1>
=<0,-6,6>
Simplify by reducing length by a factor of 6
vl=<0,-1,1>

By observing the equations of the two planes, we see that (2,0,0) is a point on the intersection, because this points satisfies both plane equations.

Thus the parametric equation of the line is
L: (2,0,0)+t(0,-1,1)
or
L: x=2, y=-t, z=t

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Write three ordered pairs for direct variation relationship where y= 12 when x= 16

Kruka [31]

Ordered pairs that work for this direct variation are (4, 3), (8, 6) and (12, 9).

In order to find these, we must first find the value of the direct variation coefficient. We can do that using the base equation y = kx and then by plugging in to find k.

y = kx

12 = k(16)

3/4 = k

Now that we have k, we can model the equation as y = 3/4x. We can also find any number of ordered pairs by using the x value and finding the y value. All of the above answers work.

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3 years ago

Which ordered pair will solve the equation 2 × 4 + x = y?

Bezzdna [24]

This answer uses NMF, which you can find out about on my profile:

Preliminary work:
Following the BIDMAS order of operations, we can calculate part of it already, and that's the 2•4, which equals 8.
Therefore, the equation now reads:
8+x = y

x = 5:
8+5 = 13
13 ≠ 16
13 ≠ y

x = 4:
8+4 = 12
12 = 12
12 = y

Therefore, the pair is (4, 12)

5 0

3 years ago

A distribution of values is normal with a mean of 188 and a standard deviation of 20.8. Find the probability that a randomly sel

padilas [110]

Answer:0.8413

Step-by-step explanation:

Mean= 188, Std Dev. =20.8, Z=(x-mean)/Std Dev

P(X less than 167.2)= P(Z less than (167.2-188)/20.8)

=P(Z less than (-20.8/20.8))

=P(z less than -1)= P(Z less 1)

The value of 1 in the normal distribution table is 0.3413

So we add 0.5 to 0.3413 =0.8413

6 0

3 years ago

a group of hikers buy 8 bags of trail mix.each nag contains 3 1\2 cups of trail mix.the trail mix is shared evenly among 12 hike

Troyanec [42]

2 1/3 cup of trail mix per hiker.

8 0

3 years ago

spin [16.1K]

Answer:

$z=\frac{0.18 -0.1}{\sqrt{\frac{0.1(1-0.1)}{100}}}=2.67$

Step-by-step explanation:

1) Data given and notation

n=100 represent the random sample taken

X=18 represent the ounce cups of coffee that were underfilled

$\hat p=\frac{18}{100}=0.18$ estimated proportion of ounce cups of coffee that were underfilled

$p_o=0.1$ is the value that we want to test

$\alpha$ represent the significance level

z would represent the statistic (variable of interest)

$p_v$ represent the p value (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to test the claim that the true proportion it's higher than 0.1 or 10%:

Null hypothesis: $p\leq 0.1$

Alternative hypothesis: $p > 0.1$

When we conduct a proportion test we need to use the z statistic, and the is given by:

$z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}$ (1)

The One-Sample Proportion Test is used to assess whether a population proportion $\hat p$ is significantly different from a hypothesized value $p_o$ .

3) Calculate the statistic

Since we have all the info requires we can replace in formula (1) like this:

$z=\frac{0.18 -0.1}{\sqrt{\frac{0.1(1-0.1)}{100}}}=2.67$

4) Statistical decision

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.

The significance level assumed for this case is $\alpha=0.05$ . The next step would be calculate the p value for this test.

Since is a one right tailed test the p value would be:

$p_v =P(Z>2.67)=0.0037$

So the p value obtained was a very low value and using the significance level given $\alpha=0.05$ we have $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance thetrue proportion is not significanlty higher than 0.1 or 10% .

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3 years ago