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melomori [17]
4 years ago
13

A hose with a larger diameter working alone can fill a swimming pool in 9 hours.A hose with a smaller diameter working alone can

fill a swimming pool in 18 hours.working together,how long would it take the two hoses to fill the swimming pool?
Mathematics
1 answer:
Arte-miy333 [17]4 years ago
8 0

The large hose fills 1 pool in 9 hours written as  1/9

The small hose fills 1 pool in 18 hours, written as 1/18


Now you have 1/9 + 1/18 = 1/x ( x is the unknown time for both hoses).

rewrite 1/9 with a common denominator as 1/18:

1/9 = 2/18


Now you have 2/18 + 1/18 = 1/x

Add the left side:

2/18 + 1/18 = 3/18


Now you have 3/18 = 1/x

Cross Multiply:

3x = 18

Divide both sides by 3"

x = 18/3

X = 6


It will take both hoses 6 hours.

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Anna [14]

Answer:

m = -6/5

Step-by-step explanation:

The points present are (-2,2) and (3,-4).

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7 0
3 years ago
Some transportation experts claim that it is the variability of speeds, rather than the level of speeds, that is a critical fact
scZoUnD [109]

Answer:

Explained below.

Step-by-step explanation:

The claim made by an expert is that driving conditions are dangerous if the variance of speeds exceeds 75 (mph)².

(1)

The hypothesis for both the test can be defined as:

<em>H</em>₀: The variance of speeds does not exceeds 75 (mph)², i.e. <em>σ</em>² ≤ 75.

<em>Hₐ</em>: The variance of speeds exceeds 75 (mph)², i.e. <em>σ</em>² > 75.

(2)

A Chi-square test will be used to perform the test.

The significance level of the test is, <em>α</em> = 0.05.

The degrees of freedom of the test is,

df = n - 1 = 55 - 1 = 54

Compute the critical value as follows:

\chi^{2}_{\alpha, (n-1)}=\chi^{2}_{0.05, 54}=72.153

Decision rule:

If the test statistic value is more than the critical value then the null hypothesis will be rejected and vice-versa.

(3)

Compute the test statistic as follows:

\chi^{2}=\frac{(n-1)\times s^{2}}{\sigma^{2}}

    =\frac{(55-1)\times 94.7}{75}\\\\=68.184

The test statistic value is, 68.184.

Decision:

cal.\chi^{2}=68.184

The null hypothesis will not be rejected at 5% level of significance.

Conclusion:

The variance of speeds does not exceeds 75 (mph)². Thus, concluding that driving conditions are not dangerous on this highway.

7 0
3 years ago
The sum of three numbers $x$ ,$y$, $z$ is 165. When the smallest number $x$ is multiplied by 7, the result is $n$. The value $n$
babymother [125]

You're given

<em>x</em> + <em>y</em> + <em>z</em> = 165

7<em>x</em> = <em>n</em>

<em>n</em> = <em>y</em> - 9

<em>n</em> = 9 + <em>z</em>

and you want to find <em>xyz</em>.

Solve the last three equations for <em>x</em>, <em>y</em>, and <em>z</em> :

7<em>x</em> = <em>n</em>   →   <em>x</em> = <em>n</em>/7

<em>n</em> = <em>y</em> - 9   →   <em>y</em> = <em>n</em> + 9

<em>n</em> = 9 + <em>z</em>   →   <em>z</em> = <em>n</em> - 9

Substitute <em>x</em>, <em>y</em>, and <em>z</em> into the first equation and solve for <em>n</em> :

<em>n</em>/7 + (<em>n</em> + 9) + (<em>n</em> - 9) = 165

<em>n</em>/7 + 2<em>n</em> = 165

<em>n</em> + 14<em>n</em> = 1155

15<em>n</em> = 1155

<em>n</em> = 77

Now solve for <em>x</em>, <em>y</em>, and <em>z</em> :

<em>x</em> = 77/7 = 11

<em>y</em> = 77 + 9 = 86

<em>z</em> = 77 - 9 = 68

Then the product is

<em>xyz</em> = 11 • 86 • 68 = 64,328

6 0
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