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3 years ago

How to substitute equations

1 answer:

5 0

When you are substituting equations, all you are doing is plugging in variables. Lets do an example..something random but easy...
y = 2x - 3
4x + 2y = 10
So since 2x + 3 equals y we are going to plug in those numbers into the second equation.
4x + 2(2x - 3) = 10
Now we distribute
4x + 4x - 6 = 10
Combine like terms.
8x - 6 = 10
Add 6 to both sides.
8x = 16
Divide.
x = 2
And thats how you substitute equations.
I hope this helps love! :)

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Six friends share cost of gift. They pay $90 and receive $42 in change. How much does each pay?

miskamm [114]

Lets look at the info we have:-

6 friends
Pay $90 and receive $42 in change.

Question:-

How much does each friend pay?

To answer this first we nee to find out how much they paed in total. lets do that 1st:-

90 - 42 = 48
They paid $48 for the gift.

CHECK OUR WORK:-

48 + 42 = 90
We were RIGHT!!

Now lets divide to find out how much each person paid:-

48 ÷ 6 = 8
Each friend pays $8.

CHECK OUR WORK:-

8 × 6 = 48
We were RIGHT!!

So, each friend pays $8 for the gift.

Hope I helped ya!! xD

7 0

4 years ago

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I'm stuck in this question and need some help for this. Thank you

marishachu [46]

I am positive it is B

6 0

4 years ago

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What is the area of the sector shown in the picture

tatuchka [14]

Answer:

The area of the sector shown is 4.75 pi

Step-by-step explanation:

First we have to know what fraction of the total circle that part represents

for that we divide 45 by 360

45/360 = 1/8

now we calculate the area of the circle and divide it by 8

a = ( π * 6² ) / 8

a = ( π * 36 ) / 8

a = π * 4.75

a = 4.75 pi

7 0

3 years ago

2. Which expression is equivalent to 3(4x + 10 = 2+3)?

ololo11 [35]

Answer: ask ggle it gives you the answer

Step-by-step explanation:

6 0

3 years ago

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The following observations were made on fracture toughness of a base plate of 18% nickel maraging steel (in ksi √in, given in in

Grace [21]

Answer:

A 90% confidence interval for the standard deviation of the fracture toughness distribution is [4.06, 6.82].

Step-by-step explanation:

We are given the following observations that were made on fracture toughness of a base plate of 18% nickel maraging steel below;

68.6, 71.9, 72.6, 73.1, 73.3, 73.5, 75.5, 75.7, 75.8, 76.1, 76.2, 76.2, 77.0, 77.9, 78.1, 79.6, 79.8, 79.9, 80.1, 82.2, 83.7, 93.4.

Firstly, the pivotal quantity for finding the confidence interval for the standard deviation is given by;

P.Q. = $\frac{(n-1) \times s^{2} }{\sigma^{2} }$ ~ $\chi^{2} __n_-_1$

where, s = sample standard deviation = $\sqrt{\frac{\sum (X - \bar X^{2}) }{n-1} }$ = 5.063

$\sigma$ = population standard deviation

n = sample of observations = 22

Here for constructing a 90% confidence interval we have used One-sample chi-square test statistics.

So, 90% confidence interval for the population standard deviation, $\sigma$ is ;

P(11.59 < $\chi^{2}__2_1$ < 32.67) = 0.90 {As the critical value of chi at 21 degrees

of freedom are 11.59 & 32.67}

P(11.59 < $\frac{(n-1) \times s^{2} }{\sigma^{2} }$ < 32.67) = 0.90

P( $\frac{ 11.59}{(n-1) \times s^{2}}$ < $\frac{1}{\sigma^{2} }$ < $\frac{ 32.67}{(n-1) \times s^{2}}$ ) = 0.90

P( $\frac{(n-1) \times s^{2} }{32.67 }$ < $\sigma^{2}$ < $\frac{(n-1) \times s^{2} }{11.59 }$ ) = 0.90

90% confidence interval for $\sigma^{2}$ = [ $\frac{(n-1) \times s^{2} }{32.67 }$ , $\frac{(n-1) \times s^{2} }{11.59 }$ ]

= [ $\frac{21 \times 5.063^{2} }{32.67 }$ , $\frac{21 \times 5.063^{2} }{11.59 }$ ]

= [16.48 , 46.45]

90% confidence interval for $\sigma$ = [ $\sqrt{16.48}$ , $\sqrt{46.45}$ ]

= [4.06 , 6.82]

Therefore, a 90% confidence interval for the standard deviation of the fracture toughness distribution is [4.06, 6.82].

5 0

3 years ago