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2 years ago

0v0 h e l p? 3r/4=1/8 (solve for r)

Mathematics

1 answer:

agasfer [191]2 years ago

3 0

Answer:

r = 1/6

Step-by-step explanation:

$\dfrac{3}{4}r=\dfrac{1}{8}\\\\\\$

Multiply both sides by 4

$4*\dfrac{3}{4}r=4*\dfrac{1}{8}\\\\3r = \dfrac{1}{2}$

Divide both sides by 3

$\dfrac{3}{3}r=\dfrac{1}{2*3}\\\\r = \dfrac{1}{6}$

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Answer: He bought 7 bags

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2 years ago

Which phrase best describes the translation from the graph y = (x – 5)2 + 7 to the graph of y = (x + 1)2 – 2?

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The parent. function shifted up by 6 units to produce x + 1 and to the left by 9 units

<h3>What is translation?</h3>

This is a way of changing the position of an object on an xy-plane.

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2 years ago

A disc has a diameter of 21 cm while a mini disc has a diameter of 14cm. Write the ratio of the mini disc diameter to the disc d

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2 years ago

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2 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