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3 years ago

4a+6b=10 2a-4b=12 what does 12a =?

1 answer:

8 0

1/2(4a + 6b = 10)
2a + 3b = 5

2a + 3b = 5
-) 2a - 4b = 12
7b = -7
b = -1

Substitute:
2a - 4(-1) = 12
2a + 4 = 12
2a = 8
a = 4

12a = 12(4) = 48

This is a little longer way to do it, but I think it's easier to understand

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James has eight coins in his pocket. All the coins are either dimes or quarters.The total value of the coins is $1.25. How many

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Answer:

he has 5d+3q

Step-by-step explanation:

since every d is .10 and every q is .25 the equation can be changed to 5(.10)+3(.25) which is equal to .5+.75 which adds up to 1.25

i did this by assuming that the amount of d is 8 at first, then change one of the 8 d to a q which will give you 7d+q, then assume another d is a q which will give you 6d+2q, repeat this until the amount of d and q add up to 1.25

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3 years ago

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Step-by-step explanation:

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3 years ago

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What number is 35% of 600

emmainna [20.7K]

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3 years ago

There are 2,000 eligible voters in a precinct. A total of 500 voters are randomly selected and asked whether they plan to vote f

Ann [662]

Answer:

$0.7 - 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.647$

$0.7 + 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.753$

And the 99% confidence interval would be given (0.647;0.753).

So the correct answer would be:

a. 0.647 and 0.753

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

Solution to the problem

The estimated population proportion for this case is:

$\hat p = \frac{350}{500}=0.7$

The confidence interval would be given by this formula

$\hat p \pm z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}$

For the 99% confidence interval the value of $\alpha=1-0.99=0.01$ and $\alpha/2=0.005$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=2.58$

And replacing into the confidence interval formula we got:

$0.7 - 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.647$

$0.7 + 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.753$

And the 99% confidence interval would be given (0.647;0.753).

So the correct answer would be:

a. 0.647 and 0.753

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3 years ago

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DochEvi [55]

Answer:

The scale factor is 0.5

Step-by-step explanation:

Divide.

2/1=2

4/2=2

8/4=2

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Now then, since this is a shrinking factor, divide 1 by the common outcome from the last section (2) to get 0.5

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3 years ago