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Goryan [66]
3 years ago
7

Kathryn deposits 100 into an account at the beginning of each 4-year period for 40 years. The account credits interest at an ann

ual effective interest rate of i. The accumulated amount in the account at the end of 40 years is X, which is 5 times the accumulated amount in the account at the end of 20 years. Find X
Mathematics
1 answer:
Inessa [10]3 years ago
8 0

Answer:

X=6.195

Attached please find equation.

Step-by-step explanation:

Let 1+i∗=(1+i)4 so that the calculation using annuity

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HELP PLEASE LOOK AT PICTURE
solniwko [45]

Answer:

It decreases.

Step-by-step explanation:

10 / d

Lets say that it was 10 / 40, which is 10 divided by 40, 0.25.

Now, it has increased to twice the amount of that.

1 / 80, 10 divided by 80, which is 0.125

So, it decreases.

4 0
4 years ago
Read 2 more answers
Pleaseee help me solve the function
schepotkina [342]

Answer:

f(x) =  \frac{3 {(2)}^{2} - 2 }{2(2) + 3}  =  \frac{12 - 2}{7}  =  \frac{10}{7}

3 0
3 years ago
Can someone help me with this and show their work and how they found the answer?
Semenov [28]

Answer:

2kg

Step-by-step explanation:

Let the sum of the other 2 bricks be R. Given that the heaviest brick weighs 2/3 times as much as the other 2 bricks in total, then the weight of the heaviest brick H in terms of the weight of the other 2 will be

H = 2/3 * R

= 2R/3

Given that the 3 bricks weigh 5kg in total then,

2R/3 + R = 5

Multiply through the equation by 3

2R + 3R = 15

5R = 15

Divide both sides by 5

R = 15/5

= 3

The weight of the heaviest brick is 2R/3. Since R = 3, the heaviest block weighs

= 2 * 3/3

= 2kg

4 0
3 years ago
John goes to a bookstore. he wants to buy at. most 25 books and spend at most $75. paperback books cost 1.75 and har cover books
Yanka [14]

Answer:

  • x + y ≤ 25
  • 1.75x + 2.50y ≤ 75

Step-by-step explanation:

  • Paperback books = x
  • Hard cover books = y

<u>Number of books:</u>

  • x + y ≤ 25

<u>Cost of books:</u>

  • 1.75x + 2.50y ≤ 75

The system above is the one we need

6 0
3 years ago
A new screening test for Lyme disease is developed for use in the general population. The sensitivity and specificity of the new
Anit [1.1K]

Answer:

predictive value of a positive test = 18.18%

predictive value of a negative test = 94.03%

Step-by-step explanation:

Sensitivity = 60% = 0.6

Specificity = 70% = 0.7

Let True Positive = TP

True Negative = TN

False Negative = FN

Sensitivity = \frac{TP}{TP + FN} \\0.6 = \frac{TP}{TP + FN} \\0.6TP + 0.6FN = TP\\0.4TP = 0.6FN\\TP = 1.5 FN

Specificity = \frac{TN}{TN + FP} \\0.7 = \frac{TN}{TN + FP} \\0.7TN + 0.7FP = TN\\0.7FP = 0.3 TN\\TN  = 7/3 FP

Prevalence = 10% = 0.1

Three hundred people are screened, T_{total} = 300

Total number of people having the disease, T_{disease} = ?

Prevalence = \frac{T_{disease} }{T_{total} } \\0.1 =  \frac{T_{disease} }{300 }\\T_{disease} = 30

T_{disease} = TP + FN\\30 = TP + FN

But TP = 1.5 FN

30 = 1.5 FN + FN

30 = 2.5 FN

FN = 30/2.5

FN = 12

TP = 1.5 FN = 1.5 * 12

TP = 18

FP + TN = T_{total} - T_{disease} \\FP + TN = 300 - 30\\FP + TN = 270\\FP + \frac{7}{3} FP = 270\\\frac{10}{3} FP = 270\\FP = 27 * 3\\FP = 81

81 + TN = 270

TN = 189

To calculate the Predictive value of positive test (PPT)

PPT = \frac{TP}{TP + FP} * 100\\PPT = \frac{18}{18+81} * 100\\PPT = \frac{18}{99} * 100\\PPT = 18.18 \%

To calculate the Predictive value of negative test (PNT)

PPT = \frac{TN}{FN + TN} * 100\\PPT = \frac{189}{189+12} * 100\\PPT = \frac{189}{201} * 100\\PPT = 94.03 \%

7 0
3 years ago
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