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3 years ago

30 points!! Help please!! Will give Brainliest!!!

Mathematics

1 answer:

Leto [7]3 years ago

3 0

Answer:

Step-by-step explanation:

Area of a trapezoid = (1/2)*(base1+base2)*height

Area = (1/2)*(15+7)*height

DC is 7 which means EF is also 7.

AB = 15

AB - EF = AE + FB = 8

And AE = FB we know that AE is 8/2 = 4

We were given AD = 5. We have a 3-4-5 right triangle and therefore DE is 4. The height of the trapezoid is 3 ft.

Area = 1/2 (15+7)*(3)

Area = (1/2)*22*3

Area = 11 * 3

Area = 33 ft^2

Your answer is B

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5. A student measures the velocity of the water in

Oksana_A [137]

Answer:

The percent deviation = 16.67%

Step-by-step explanation:

Please kindly check the attached for more information

8 0

3 years ago

I realy need help please

hjlf

Answer:

x = 128 degrees

Step-by-step explanation:

First figure out the angle inside the triangle

1st step: add 55 and 73 together:

⇒ 55 + 73 = 128

2nd step: subtract the sum from 180:

⇒ 180 - 128 = 52

to find x, take 180 again and then subtract 52 from it:

⇒ 180 - 52 = 128

5 0

3 years ago

Read 2 more answers

A tank contains 60 kg of salt and 1000 L of water. Pure water enters a tank at the rate 6 L/min. The solution is mixed and drain

MissTica

Answer:

(a) 60 kg; (b) 21.6 kg; (c) 0 kg/L

Step-by-step explanation:

(a) Initial amount of salt in tank

The tank initially contains 60 kg of salt.

(b) Amount of salt after 4.5 h

$\text{Let A = mass of salt after t min}\\\text{and }r_{i} = \text{rate of salt coming into tank}\\\text{and }r_{0} =\text{rate of salt going out of tank}$

(i) Set up an expression for the rate of change of salt concentration.

$\dfrac{\text{d}A}{\text{d}t} = r_{i} - r_{o}\\\\\text{The fresh water is entering with no salt, so}\\ r_{i} = 0\\r_{o} = \dfrac{\text{3 L}}{\text{1 min}} \times \dfrac {A\text{ kg}}{\text{1000 L}} =\dfrac{3A}{1000}\text{ kg/min}\\\\\dfrac{\text{d}A}{\text{d}t} = -0.003A \text{ kg/min}$

(ii) Integrate the expression

$\dfrac{\text{d}A}{\text{d}t} = -0.003A\\\\\dfrac{\text{d}A}{A} = -0.003\text{d}t\\\\\int \dfrac{\text{d}A}{A} = -\int 0.003\text{d}t\\\\\ln A = -0.003t + C$

(iii) Find the constant of integration

$\ln A = -0.003t + C\\\text{At t = 0, A = 60 kg/1000 L = 0.060 kg/L} \\\ln (0.060) = -0.003\times0 + C\\C = \ln(0.060)$

(iv) Solve for A as a function of time.

$\text{The integrated rate expression is}\\\ln A = -0.003t + \ln(0.060)\\\text{Solve for } A\\A = 0.060e^{-0.003t}$

(v) Calculate the amount of salt after 4.5 h

a. Convert hours to minutes

$\text{Time} = \text{4.5 h} \times \dfrac{\text{60 min}}{\text{1h}} = \text{270 min}$

b.Calculate the concentration

$A = 0.060e^{-0.003t} = 0.060e^{-0.003\times270} = 0.060e^{-0.81} = 0.060 \times 0.445 = \text{0.0267 kg/L}$

c. Calculate the volume

The tank has been filling at 6 L/min and draining at 3 L/min, so it is filling at a net rate of 3 L/min.

The volume added in 4.5 h is

$\text{Volume added} = \text{270 min} \times \dfrac{\text{3 L}}{\text{1 min}} = \text{810 L}$

Total volume in tank = 1000 L + 810 L = 1810 L

d. Calculate the mass of salt in the tank

$\text{Mass of salt in tank } = \text{1810 L} \times \dfrac{\text{0.0267 kg}}{\text{1 L}} = \textbf{21.6 kg}$

(c) Concentration at infinite time

$\text{As t $\longrightarrow \, -\infty,\, e^{-\infty} \longrightarrow \, 0$, so A $\longrightarrow \, 0$.}$

This makes sense, because the salt is continuously being flushed out by the fresh water coming in.

The graph below shows how the concentration of salt varies with time.

3 0

3 years ago

A machining company needs to manufacture more than 20 fixtures in a day. The company uses five identical machines to make the fi

nikklg [1K]

Answer:

A. 5x>20

Step-by-step explanation:

Because the company has to produce more than 20 fixtures you need greater than 20 and you have 5 machines time the number they produce.

Hope this helps, if it does please mark brainliest!!

3 0

3 years ago

If a number added to five is divided by the difference of the number and two, the result is three-fourths. Find the number.

alexandr1967 [171]

Answer:

x = - 26

Step-by-step explanation:

Let the number be x.

According to the question,

$\frac{x+5}{x-2} = \frac{3}{4}\\$

Cross multiplying 4 & 3 gives :-

$4(x+5)=3(x-2)$

And solving this eqn. gives :-

$4(x+5)=3(x-2)\\=> 4x+20=3x-6\\=>4x-3x=-20-6\\=>x=-26$

Verification :-

(putting the value of x = -26 )

$\frac{x+5}{x-2} \\\\=>\frac{-26+5}{-26-2} \\\\=> \frac{-21}{-28} \\\\=>\frac{21}{28}$

Reducing $\frac{21}{28}$ by 7 gives $\frac{3}{4}$ .

5 0

4 years ago