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Gennadij [26K]
3 years ago
6

To solve work problems, find the portion of the job each person completes in 1 unit of time. The sum of these portions is the po

rtion of the job completed in 1 unit of time. You can mop a floor in 8 minutes. Your friend can mop the same floor in 12 minutes. Working together, how much time does it take to mop the floor?
Mathematics
1 answer:
Gwar [14]3 years ago
6 0

Answer:

  4.8 minutes

Step-by-step explanation:

Using the given hint, working together, the amount of floor mopped in 1 minute is ...

  1/8 + 1/12 = 3/24 +2/24 = 5/24 . . . . jobs/minute

The reciprocal of that is the rate in terms of minutes per job. Thus the entire job takes 24/5 = 4.8 minutes.

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Help me with Perpendicular angles
DiKsa [7]

Answer:

x = 50°

x = 70°

Step-by-step explanation:

A right angle is indicated by a small box.

The angles shown are right angles = 90° each. Therefore:

✔️x + 40° = 90°

Subtract 40° from each side

x = 90° - 40°

x = 50°

✔️x + 20° = 90°

Subtract 20° from each side

x = 90° - 20°

x = 70°

6 0
2 years ago
The pressure and volume of an expanding gas are related by the formula PV^b=C, where b and C are constants (this holds in adiaba
bazaltina [42]

The dP/dt of the adiabatic expansion is -42/11 kPa/min

<h3>How to calculate dP/dt in an adiabatic expansion?</h3>

An adiabatic process is a process in which there is no exchange of heat from the system to its surrounding neither during expansion nor during compression

Given b=1.5, P=7 kPa, V=110 cm³, and dV/dt=40 cm³/min

PVᵇ = C

Taking logs of both sides gives:

ln P + b ln V = ln C

Taking partial derivatives gives:

\frac{1}{P}\frac{∂P}{∂t}  + \frac{b}{V}\frac{∂V}{∂t} = 0

Substitutituting the values b, P, V and dV/dt into the derivative above:

1/7 x dP/dt +  1.5/110 x 40 = 0

1/7 x dP/dt +  6/11 = 0

1/7 x dP/dt = - 6/11

dP/dt = - 6/11 x 7

dP/dt = -42/11 kPa/min

Therefore, the value of  dP/dt is -42/11 kPa/min

Learn more about adiabatic expansion on:

brainly.com/question/6966596

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4 0
1 year ago
Doug dives from a platform that is 7.5 meters above water. His dive takes him 2.1 meters below the surface of the water. How far
kow [346]
Not so sure.. but I got 9.6 meters below water level.
4 0
3 years ago
Index notation simplify 4^9 x 4^3
LenKa [72]

Answer:

4^{12}

Step-by-step explanation:

Using the rule of exponents

a^{m} × a^{n} = a^{(m+n)} , then

4^{9} × 4^{3} = 4^{(9+3)} = 4^{12}

7 0
2 years ago
Using differential calculus, maximize the volume of a box made of cardboard (top is open) as shown in Figure A. 15, subject to t
lana [24]

The maximum volume of the box is 40√(10/27) cu in.

Here we see that volume is to be maximized

The surface area of the box is 40 sq in

Since the top lid is open, the surface area will be

lb + 2lh + 2bh = 40

Now, the length is equal to the breadth.

Let them be x in

Hence,

x² + 2xh + 2xh = 40

or, 4xh = 40 - x²

or, h = 10/x - x/4

Let f(x) = volume of the box

= lbh

Hence,

f(x) = x²(10/x - x/4)

= 10x - x³/4

differentiating with respect to x and equating it to 0 gives us

f'(x) = 10 - 3x²/4 = 0

or, 3x²/4 = 10

or, x² = 40/3

Hence x will be equal to 2√(10/3)

Now to check whether this value of x will give us the max volume, we will find

f"(2√(10/3))

f"(x) = -3x/2

hence,

f"(2√(10/3)) = -3√(10/3)

Since the above value is negative, volume is maximum for x = 2√(10/3)

Hence volume

= 10 X 2√(10/3)  -  [2√(10/3)]³/4

= 2√(10/3) [10 - 10/3]

= 2√(10/3) X 20/3

= 40√(10/27) cu in

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Complete Question

(Image Attached)

3 0
1 year ago
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