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Katen [24]
4 years ago
10

ariana starts with 100 milligram of a radioactive substance the amount of the substance decreases by 20% each week each number f

or weeks w. the expression 100 (-0.2) finds the amount radioactive substance remaining w weeks.
Mathematics
2 answers:
Anuta_ua [19.1K]4 years ago
7 0

The required expression is 100 - 0.2w

Step-by-step explanation:

Given,

Amount of radioactive substance = 100 mg

The substance decreases by 20% each week.

To find the remaining amount of the in w weeks.

Now,

Each week 20% = 0.2 of the substance will be decreased.

So, in w weeks 0.2×w of the the substance will be decreased.

Hence,

The remaining substance = 100 - 0.2w

dexar [7]4 years ago
6 0

Answer:

It is the difference between the initial amount and the percent decrease.

Step-by-step explanation:

i think....

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1) Anna and Jason have summer jobs stuffing envelopes for two different companies. Anna earns $20 for every 400 envelopes she fi
AleksAgata [21]

Answer:

The answer is below

Step-by-step explanation:

A) i)

For Anna initially, she has $0 from making 0 envelopes. After making 400 envelopes she has $20. Let x represent the number of envelopes and y the earnings. Hence this can be represented by the points (0, 0) and (400, 20). Using the equation of a line:

y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\\\y-0=\frac{20-0}{400-0}(x-0)\\\\y=\frac{1}{20} x

The table is:

x:   200     400       600     800     1000

y:    10        20          30        40       50

ii)

For Jason initially, he has $0 from making 0 envelopes. For every 250 envelopes he has $10. Let x represent the number of envelopes and y the earnings. Hence this can be represented by the points (0, 0) and (250, 10). Using the equation of a line:

y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\\\y-0=\frac{10-0}{250-0}(x-0)\\\\y=\frac{1}{25} x

The table is:

x:   200     400       600     800     1000

y:    8         16           24        32       40

The graph is plotted using geogebra online graphing

b) From the table above we can see that Anna makes more stuffing than Jason.

c) Anna has a savings of $100. Hence this can be represented by the points (0, 100) and (250, 10). Using the equation of a line:

y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\\\y-100=\frac{20-0}{400-100}(x-0)\\\\y=\frac{1}{15} x+100

We can see from the graph that there is a y intercept at 100. That is the earnings starts from 100.

The equation of a line is given as y = mx + b, where m is the slope and b is the y intercept (initial value)

For the first graph, the slope is 1/20 and the initial value is 0 while for the second graph the slope is 1/15 and the initial value is 100

D) The line pass through (10, 10) and (100, 40), hence:

y-y_1=\frac{y_2-y_1}{x_2-x_1} (x-x_1)\\\\y-10=\frac{40-10}{100-10}(x-10)\\\\y-10=\frac{1}{3} (x-10)\\\\y=\frac{1}{3}x+\frac{20}{3}

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3 years ago
One-half the sum of x,y, and z
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The keyword is "sum" which tells you x, y, and z are being added. One half of the sum means that the sum of the three numbers is going to be divided by 2.

x + y + z
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3 0
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What is the correct classification of the system of equations below? 14x + 2y = 10 y + 7x = -5 parallel coincident intersecting
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Ralph buys a desk that regularly sells for $250 and a desk chair that regularly sells for $145. both items are on sale at 15% of
Lunna [17]
C) (0.85 + x/100)(250+145) does not give the correct answer.

Explanation
A) works; adding the two costs together is 250+145=395.  We multiply this by 0.85 because 100%-15%=85%=0.85.  We also have x% tax, which is represented by x/100, added to 100% of the value, or 1.00.  Altogether this gives us 
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= 395(0.85) + 395(0.0085x)
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C) does not work; (0.85+x/100)(395) does not take into consideration that you are finding the tax after taking the 85%.  This will simplify out to
0.85*395 + (x/100)(395) = 335.75 + 395x/100 = 335.75 + 3.95x, which is too much.
D) works; simplifying the expression from A, we have 395(0.85) + 395(0.0085x) = 335.75 + 3.3575x.
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Which of the following best describes similar figures that are not congruent?
Drupady [299]

Answer:

A

Step-by-step explanation:

Being similar means that the shapes will have the same shape and dilation factor between sides, but if they are not congruent then the size will not be the same.

7 0
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