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3 years ago

Peter was thinking of a number. Peter divides by 7, then adds 5 to get an answer of 13. What was the original number?

Mathematics

2 answers:

Mila [183]3 years ago

7 0

Answer:

Step-by-step explanation:

5-13=8

7*8=56

evablogger [386]3 years ago

7 0

Answer:

the answer is 56(fifty six)....

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Equavlent to (-18x-12)-13x+17

Setler79 [48]

-31x+5 is the same as (-18x-12)-13x+17

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3 years ago

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Oil is pumped continuously from a well at a rate proportional to the amount of oil left in the well. Initially there were millio

JulijaS [17]

Answer:

The amount of oil was decreasing at 69300 barrels, yearly

Step-by-step explanation:

Given

$Initial =1\ million$

$6\ years\ later = 500,000$

Required

At what rate did oil decrease when 600000 barrels remain

To do this, we make use of the following notations

t = Time

A = Amount left in the well

So:

$\frac{dA}{dt} = kA$

Where k represents the constant of proportionality

$\frac{dA}{dt} = kA$

Multiply both sides by dt/A

$\frac{dA}{dt} * \frac{dt}{A} = kA * \frac{dt}{A}$

$\frac{dA}{A} = k\ dt$

Integrate both sides

$\int\ {\frac{dA}{A} = \int\ {k\ dt}$

$ln\ A = kt + lnC$

Make A, the subject

$A = Ce^{kt}$

$t = 0\ when\ A =1\ million$ i.e. At initial

So, we have:

$A = Ce^{kt}$

$1000000 = Ce^{k*0}$

$1000000 = Ce^{0}$

$1000000 = C*1$

$1000000 = C$

$C =1000000$

Substitute $C =1000000$ in $A = Ce^{kt}$

$A = 1000000e^{kt}$

To solve for k;

$6\ years\ later = 500,000$

i.e.

$t = 6\ A = 500000$

So:

$500000= 1000000e^{k*6}$

Divide both sides by 1000000

$0.5= e^{k*6}$

Take natural logarithm (ln) of both sides

$ln(0.5) = ln(e^{k*6})$

$ln(0.5) = k*6$

Solve for k

$k = \frac{ln(0.5)}{6}$

$k = \frac{-0.693}{6}$

$k = -0.1155$

Recall that:

$\frac{dA}{dt} = kA$

Where

$\frac{dA}{dt}$ = Rate

So, when

$A = 600000$

The rate is:

$\frac{dA}{dt} = -0.1155 * 600000$

$\frac{dA}{dt} = -69300$

<em>Hence, the amount of oil was decreasing at 69300 barrels, yearly</em>

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2 years ago

10. Two plots of land, one square and other rectangle have same perimeter. If the rectangular field is of size 90 m by 70 m, whi

masya89 [10]

Answer:

Here is your answer.

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2 years ago

I don’t understand this

Anit [1.1K]

it is 1/2 because it is greater

4 0

3 years ago

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A box has a length of 4 inches and a width of 8 inches. If the volume is 192 cubic inches, what is the height of the box?

melamori03 [73]

C) 6 inches

4•8=32
192/32 = 6

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3 years ago