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3 years ago

8

cookies are on sal today each cookie cost $0.75 less than the normal price. right now if oyu buy 7 of them it will only cost you

$2.80

1 answer:

Gemiola [76]3 years ago

3 0

Answer:

im assuming you want the original price, so $1.15

Step-by-step explanation:

2.80 / 7 = 0.40

0.75 + 0.40 = 1.15

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In Jeremiah class

Irina18 [472]

Answer:

2/5 = 4/10

4/10 = 40%

Explanation:

2/5 is a simplified fraction, and one of the bigger fractions it’s made by 4/10. Do you can use 4/10, but can also use 8/20, 20/50, 40/100, so on. Since we know that any fraction that of ten can be turned into a percentage easily (2/10=20%, 5/10=50%,9/10=%90), then 4/10 is equal to 40%. So 40% of the people in Jeremiah’s class are boys.

6 0

2 years ago

Which statements are true about the rules of division?

masya89 [10]

Answer:

where is the list at?

Step-by-step explanation:

3 0

3 years ago

Mary uses 56 inches of yarn to form a rectangle. if the rectangle is 4 inches wide what is it length

uranmaximum [27]

We know, area = length * width
56 = l * 4
l = 56 / 4
l = 14

So, the length is 14

Hope this helps!

6 0

3 years ago

Read 2 more answers

Find the length of the line below.

Volgvan

Answer:

2.1cm

Step-by-step explanation:

the line is 2cm and 1mm

7 0

2 years ago

Mr. Ratchett, an elderly American, was found murdered in his train compartment on the Orient Express at 7 AM. When his body was

nasty-shy [4]

Answer: Mr. Ratchett died approximately at 2AM.

Step-by-step explanation: <u>Newton's</u> <u>Law</u> <u>of</u> <u>Cooling</u> shows the cooling rate between a body and the environment, by stating that the rate is proportional to the difference in temperatures between them.

Mathematically, it is represented as:

$\frac{dQ}{dt}=\alpha.A.(T_{s}-T)$

This differential equation solved, gives the solution:

$T(t)=T_{s}+(T_{0}-T_{s})e^{-kt}$

where

$T_{s}$ is temperature of the environment

$T_{0}$ is the initial temperature of the body

k is a parameter dependent of heat transfer coefficient, heat capacity and area of the body

t is time required to change the temperature

For the murder on the Orient Express, first determine parameter k.

In 1 hour, Mr. Ratchett's body decrease 1°:

$27=22+(28-22)e^{-1k}$

$5=6e^{-k}$

$e^{-k}=\frac{5}{6}$

$ln(e^{-k})=ln(0.834)$

k = 0.1823

Using the parameter, find estimate time:

$28=22+(37-22)e^{-0.1823t}$

$6=15e^{-0.1823t}$

$ln(e^{-0.1823t})=ln(0.4)$

0.1823t = 0.9163

$t=\frac{0.9163}{0.1823}$

t ≈ 5 hours

The body was found at 7AM. So, it took approximately 5 hours to cool down to 28° at that time. Therefore, Mr. Ratchett died at 2AM.

5 0

3 years ago