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3 years ago

63 miles in 270 minutes, what is the average speed in miles per hour

Mathematics

1 answer:

bearhunter [10]3 years ago

5 0

Answer:

14 miles per hour

Step-by-step explanation:

Convert 270 minutes to hours first= 4.5hrs

Then divide 63 by 4.5= 14

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A store is having a sale on chocolate chips and walnuts. For 3 pounds of chocolate chips and 5 pounds of walnuts, the total cost

mrs_skeptik [129]

Answer:

Step-by-step explanation:

3c + 5w = 16

6c + 2w = 22

-6c - 10w = -32

6c + 2w = 22

-8w = -10

w = 10/8 = 5/4 = $1.25 per lb

3c + 5(1.25) = 16

3c + 6.25 = 16

3c = 9.75

c = $3.25 per lb

5 0

3 years ago

12 girls are having a sleepover at a house, the food there can last them for 10 days. If 3 more girls came over, how long will f

FrozenT [24]

Answer:

The answer is 8

Step-by-step explanation:

12*10=120 120/15=8

8 0

3 years ago

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>

7 0

2 years ago

Help pleaseeeeeewwewwww

aleksandr82 [10.1K]

Answer:

x is greater than 3

less than 45

Step-by-step explanation:

5 0

3 years ago

Read 2 more answers

Can somebody help me plz with number 13,14,15,16,17

yuradex [85]

13. There are 3 feet in a yard. You divide 34 by 3 and get 11 with one left over. So it should be 11 yards and 1 foot.
14. 16 oz. = 1 lb. If you multiply 16 (oz) x 8 (lbs.) you get 128 ounces.

5 0

3 years ago