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3 years ago

14

Maria can clean the entire house in two hours. Her sister, Sasha, can clean the house in three hours. How long would it take for

two of them to do the job together?

1 answer:

lisabon 2012 [21]3 years ago

3 0

Maria do 1/2 work in 1 hour
Sasha do 1/3 work in 1 hour

Thus,
1/2+1/3=5/6 work in 1 hour
5/6 work in = 1 hour
1 work in =6/5=1.2 hours =72 minutes

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What is the answer to this solution. -7r−4≥ 4r+2

tia_tia [17]

Answer:

The solution is:

$-7r-4\ge \:\:4r+2\quad \::\quad \:\begin{bmatrix}\mathrm{Solution:}\:&\:r\le \:\:-\frac{6}{11}\:\\ \:\:\mathrm{Decimal:}&\:r\le \:\:-0.54545\dots \:\\ \:\:\mathrm{Interval\:Notation:}&\:(-\infty \:\:,\:-\frac{6}{11}]\end{bmatrix}$

Please check the attached line graph below.

Step-by-step explanation:

Given the expression

$-7r-4\ge \:4r+2$

Add 4 to both sides

$-7r-4+4\ge \:4r+2+4$

Simplify

$-7r\ge \:4r+6$

Subtract 4r from both sides

$-7r-4r\ge \:4r+6-4r$

Simplify

$-11r\ge \:6$

Multiply both sides by -1 (reverses the inequality)

$\left(-11r\right)\left(-1\right)\le \:6\left(-1\right)$

Simplify

$11r\le \:-6$

Divide both sides by 11

$\frac{11r}{11}\le \frac{-6}{11}$

Simplify

$r\le \:-\frac{6}{11}$

Therefore, the solution is:

$-7r-4\ge \:\:4r+2\quad \::\quad \:\begin{bmatrix}\mathrm{Solution:}\:&\:r\le \:\:-\frac{6}{11}\:\\ \:\:\mathrm{Decimal:}&\:r\le \:\:-0.54545\dots \:\\ \:\:\mathrm{Interval\:Notation:}&\:(-\infty \:\:,\:-\frac{6}{11}]\end{bmatrix}$

Please check the attached line graph below.

7 0

3 years ago

F(z) = (z - 5)(2x + 7) (73 = 3) has zeros at x = -3.5, x=3/7 , x=5 What is the sign of f on the interval 3/7 < x <5?

Gwar [14]

<h3>Answer: Negative</h3>

======================================================

Explanation:

3/7 = 0.42857 approximately

Pick a number between that value and 5, not including either endpoint. Let's say we pick x = 2

Plug x = 2 into the f(x) function

f(x) = (x - 5)(2x + 7)(7x-3)

f(2) = (2 - 5)(2*2 + 7)(7*2-3)

f(2) = (2 - 5)(4 + 7)(14-3)

f(2) = (-3)(11)(11)

f(2) = -363

The actual result doesn't matter. All we're after is whether the result is positive or negative. We see the result is negative. This means f(x) is negative when 3/7 < x < 5. The f(x) curve is below the x axis on this interval.

3 0

3 years ago

Monica took a survey of her classmates' hair and eye color. The results are in the table below.

jolli1 [7]

Answer:

let R represent red hair

let G represent green eyes

<em>from</em><em> </em><em>Baye's</em><em> </em><em>theorem</em><em>:</em>

<em> $P( \frac{R}{G} ) = \frac{P(RnG)}{P(G)}$ </em>

P(RnG) = 5

$P(G) = { \sum}(green \: hair) \\ = (3 + 5 + 5) \\ = 13$

Therefore:

$P( \frac{R}{G} ) = \frac{5}{13} \\ = 0.385$

The conditional relative frequency = 0.385

4 0

3 years ago

Isaac goes to an amusement park where tickets for the rides cost $10 per sheet and tickets for the shows cost $15 each.

Digiron [165]

Yeah the tickets is over-priced. Sure the question is not missing ?

7 0

3 years ago

Read 2 more answers

Using the simple random sample of weights of women from a data set, we obtain these sample statistics: nequals45 and x overbar

Tomtit [17]

Answer: (141.1, 156.48)

Step-by-step explanation:

Given sample statistics : $n=45$

$\overline{x}=148.79\text{ lb}$

$\sigma=31.37\text{ lb}$

a) We know that the best point estimate of the population mean is the sample mean.

Therefore, the best point estimate of the mean weight of all women = $\mu=148.79\text{ lb}$

b) The confidence interval for the population mean is given by :-

$\mu\ \pm E$ , where E is the margin of error.

Formula for Margin of error :-

$z_{\alpha/2}\times\dfrac{\sigma}{\sqrt{n}}$

Given : Significance level : $\alpha=1-0.90=0.1$

Critical value : $z_{\alpha/2}=z_{0.05}=\pm1.645$

Margin of error : $E=1.645\times\dfrac{31.37}{\sqrt{45}}\approx 7.69$

Now, the 90% confidence interval for the population mean will be :-

$148.79\ \pm\ 7.69 =(148.79-7.69\ ,\ 148.79+7.69)=(141.1,\ 156.48)$

Hence, the 90% confidence interval estimate of the mean weight of all women= (141.1, 156.48)

3 0

3 years ago