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3 years ago

(2x-6)+4(x-3) I need help

Mathematics

2 answers:

lys-0071 [83]3 years ago

4 0

Answer:

6x-18

x=-3

Step-by-step explanation:

DIA [1.3K]3 years ago

3 0

(2x - 6) + 4(x - 3)
2x - 6 + 4x - 12
6x - 18

The answer is 6x - 18.

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A store is offering a $45 mail in rebate on all color printers. Luis is looking at different color printers that range in price

DochEvi [55]

Answer: Range between he can expect to spend after the rebate is in between $115 and $240.

Step-by-step explanation:

Since we have given that

Amount a store is offering in rebate = $45

Range in price of different color printers is given by

$160 to $285.

If Price of color printers = $160

Amount he can expect after the rebate is given by

$\$160-\$45\\\\=\$115$

Similarly, if price of color printers = $285

Amount he can expect after the rebate is given by

$\$285-\$45\\\\=\$240$

So, Range between he can expect to spend after the rebate is in between $115 and $240.

3 0

3 years ago

A random sample of 20 students yielded a mean of ¯x = 72 and a variance of s2 = 16 for scores on a college placement test in mat

Helen [10]

Answer:

The 98% confidence interval for the variance in the pounds of impurities would be $8.400 \leq \sigma^2 \leq 39.827$ .

Step-by-step explanation:

1) Data given and notation

$s^2 =16$ represent the sample variance

s=4 represent the sample standard deviation

$\bar x$ represent the sample mean

n=20 the sample size

Confidence=98% or 0.98

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 mean or variance 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.

The Chi square distribution is the distribution of the sum of squared standard normal deviates .

2) Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

On this case the sample variance is given and for the sample deviation is just the square root of the sample variance.

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

$df=n-1=20-1=19$

Since the Confidence is 0.98 or 98%, the value of $\alpha=0.02$ and $\alpha/2 =0.01$ , and we can use excel, a calculator or a table to find the critical values.