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3 years ago

A shirt is on sale for $30. It was originally $40 What is the percent of the decrease?

Mathematics

1 answer:

SpyIntel [72]3 years ago

4 0

Answer:

25% percent

Step-by-step explanation:

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The radius of a circle is 7 centimeters

amm1812

a) So we know the formula of finding the circumference: 2*pi*R.

Assuming we make pi = 3.14: 2 * 3.14 * 7 = 43.96.

b) We also know the formula of finding the area: pi * r^2.

3.14 * 7^2. Using PEMDAS:

3.14 * 49 = 153.86

8 0

2 years ago

A 41 gram sample of a substance that's used to detect explosives has a k-value of 0.1392. Find the substance's half life, in day

-BARSIC- [3]

Answer:

The substance half-life is of 4.98 days.

Step-by-step explanation:

Equation for an amount of a decaying substance:

The equation for the amount of a substance that decay exponentially has the following format:

$A(t) = A(0)e^{-kt}$

In which k is the decay rate, as a decimal.

k-value of 0.1392.

This means that:

$A(t) = A(0)e^{-0.1392t}$

Find the substance's half life, in days.

This is t for which $A(t) = 0.5A(0)$ . So

$A(t) = A(0)e^{-0.1392t}$

$0.5A(0) = A(0)e^{-0.1392t}$

$e^{-0.1392t} = 0.5$

$\ln{e^{-0.1392t}} = \ln{0.5}$

$-0.1392t = \ln{0.5}$

$t = -\frac{\ln{0.5}}{0.1392}$

$t = 4.98$

The substance half-life is of 4.98 days.

5 0

2 years ago

Geometry :))), please help me

amm1812

Answer:

x = -5

Step-by-step explanation:

Since these two triangles are similar, the ratio between the corresponding lengths of each triangle will be the same.

This means the ratio between one side of each triangle (e.g. AD and DC) will be the same as the ratio between a different side of each triangle (e.g. BE and BC).

So, to create an equation for the sides which contain the unknown 'x', we must first find the ratio between the two sides by using a different set of sides.

On the right side we are given 9 for AD, and 18 for DC.

9/18 = 0.5

This means that the extra length of the larger triangle from the smaller one (AD) is half the length of the smaller triangle (DC). We can use this to make an equation for x:

If AD/DC = 0.5, then BE/EC will also = 0.5

BE = x+23

EC = x+41

Therefore:

$\frac{x+23}{x+41} = 0.5$

Now we can solve by multiplying both sides by x+41 to eliminate the fraction:

$x+23=0.5(x+41)$

Now we multiply out the brackets and move the terms to different sides:

$x+23=0.5x+20.5$

$0.5x = -2.5$

$x = -5$

And if we substitute the -5 into the equations:

-5+23 = 18

-5 + 41 = 36

We will see that -5 does indeed give us the same ratio between the lengths:

18/36 = 0.5

Hope this helped!

4 0

2 years ago

a bonus of 4200 is shared by 10 people who works for a company.40% of the bonus is shared equally between 3 managers the rest of

oee [108]

Step-by-step explanation:

if each the bonus is shared equally each will get 420

if 40% is shared by managers each manager will get 560

if 7 sales persons share 60% each will get 360

therefore Peter salesperson will get 360

but he thinks he will get 336 because if 420 is 125% that is including his extra 25% then hundred percent of the 420 is 336 which is not what he will get there for Janet is correct

7 0

2 years ago

Ratio and Proportion problem<br>Please help meh

Anarel [89]

Answer:

hope its helpful to uh.......

4 0

2 years ago

A shirt is on sale for $30. It was originally $40 What is the percent of the decrease?​

A shirt is on sale for $30. It was originally $40 What is the percent of the decrease?