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stiks02 [169]
2 years ago
8

If it takes Daniel 9 hours to clean an office building and it takes Mark 6 hours, how long would it take the two of them, workin

g together, to clean the building?
Mathematics
2 answers:
3241004551 [841]2 years ago
8 0

Answer: it will take 3.6 hours

Step-by-step explanation:

If it takes Daniel 9 hours to clean an office building, it means that the rate at which he cleans the office building per hour is 1/9

If it takes Mark 6 hours to clean the office building, it means that the rate at which Mark cleans the office building per hour is 1/6

If they work together, they would work simultaneously and their individual rates are additive. This means that their combined working rate would be

1/9 + 1/6 = (6 + 9)/54 = 15/54

Assuming it takes t hours for both of them to clean the office working together, the working rate per hour would be 1/t. Therefore,

15/54 = 1/t

t = 54/15 = 3.6 hours

padilas [110]2 years ago
7 0

It would be 3 hours. This is 3 hours because the problem says that daniel takes 9 hours to clean and office building and mark takes 6 hours so if you subtract 9hours from 6 hours it would be 3 hours total. Now this can be 2 answers it can also be 15 hours if you were to add 9 hours to 6 hours.

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Answer:

The study is an observational study.

Step-by-step explanation:

Observational study: In research methods, the term "observational study" is determined as one of the different studies that are being conducted by the researchers to observe or study the effects of a specific risk factor, treatment, diagnostic test, or some other intervention in the absence of an effort to change which participants are being exposed and which is not being exposed to it.

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3 years ago
Is it possible or not<br> possible to draw a<br> triangle with sides<br> lengths of 4, 5 and 7?
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The difference between the two roots of the equation 3x^2+10x+c=0 is 4 2/3 . Find the solutions for the equation.
andrezito [222]

Answer:

Given the equation: 3x^2+10x+c =0

A quadratic equation is in the form: ax^2+bx+c = 0 where a, b ,c are the coefficient and a≠0 then the solution is given by :

x_{1,2} = \frac{-b\pm \sqrt{b^2-4ac}}{2a} ......[1]

On comparing with given equation we get;

a =3 , b = 10

then, substitute these in equation [1] to solve for c;

x_{1,2} = \frac{-10\pm \sqrt{10^2-4\cdot 3 \cdot c}}{2 \cdot 3}

Simplify:

x_{1,2} = \frac{-10\pm \sqrt{100- 12c}}{6}

Also, it is given that the difference of two roots of the given equation is 4\frac{2}{3} = \frac{14}{3}

i.e,

x_1 -x_2 = \frac{14}{3}

Here,

x_1 = \frac{-10 + \sqrt{100- 12c}}{6} ,     ......[2]

x_2= \frac{-10 - \sqrt{100- 12c}}{6}       .....[3]

then;

\frac{-10 + \sqrt{100- 12c}}{6} - (\frac{-10 + \sqrt{100- 12c}}{6}) = \frac{14}{3}

simplify:

\frac{2 \sqrt{100- 12c} }{6} = \frac{14}{3}

or

\sqrt{100- 12c} = 14

Squaring both sides we get;

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Subtract 100 from both sides, we get

100-12c -100= 196-100

Simplify:

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c = 8

Substitute the value of c in equation [2] and [3]; to solve x_1 , x_2

x_1 = \frac{-10 + \sqrt{100- 12\cdot 8}}{6}

or

x_1 = \frac{-10 + \sqrt{100- 96}}{6} or

x_1 = \frac{-10 + \sqrt{4}}{6}

Simplify:

x_1 = \frac{-4}{3}

Now, to solve for x_2 ;

x_2 = \frac{-10 - \sqrt{100- 12\cdot 8}}{6}

or

x_2 = \frac{-10 - \sqrt{100- 96}}{6} or

x_2 = \frac{-10 - \sqrt{4}}{6}

Simplify:

x_2 = -2

therefore, the solution for the given equation is: -\frac{4}{3} and -2.


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Answer:

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Step-by-step explanation:

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