answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
larisa [96]
2 years ago
9

Consider a disease whose presence can be identified by carrying out a blood test. Let p denote the probability that a randomly s

elected individual has the disease. Suppose n individuals are independently selected for testing. One way to proceed is to carry out a separate test on each of the n blood samples. A potentially more economical approach, group testing, was introduced during World War II to identify syphilitic men among army inductees. First, take a part of each blood sample, combine these specimens, and carry out a single test. If no one has the disease, the result will be negative, and only the one test is required. If at least one individual is diseased, the test on the combined sample will yield a positive result, in which case the n individual tests are then carried out. [The article "Random Multiple-Access Communication and Group Testing"† applied these ideas to a communication system in which the dichotomy was active/idle user rather than diseased/nondiseased.] If p = 0.15 and n = 5, what is the expected number of tests using this procedure? (Round your answer to three decimal places.)
Mathematics
1 answer:
kifflom [539]2 years ago
3 0

Answer:

The expected number of tests, E(X) = 6.00

Step-by-step explanation:

Let us denote the number of tests required by X.

In the case of 5 individuals, the possible value of x are 1, if no one has the disease, and 6, if at least one person has the disease.

To find the probability that no one has the disease, we will consider the fact that the selection is independent. Thus, only one test is necessary.

Case 1: P(X=1) = [P (not infected)]⁵

                       = (0.15 - 0.1)⁵

            P(X=1) = 3.125*10⁻⁷

Case 2: P(X=6) = 1- P(X=1)

                        = 1 - (1 - 0.1)⁵

               P(X=6) = (1 - 3.125*10⁻⁷) = 0.999999

               P(X=6) = 1.0

We can then use the previously determined values to compute the expected number of tests.

E(X) = ∑x.P(X=x)

      = (1).(3.125*10⁻⁷) + 6.(1.0)

 E(X)  =  E(X) = 6.00

Therefore, the expected number of tests, E(X) = 6.00

You might be interested in
If 2 tacos and 5 drinks cost $20, And three tacos and five drinks cost $25 how much does a taco cost
san4es73 [151]
A taco costs $5
This is because there was no difference in the cost except for $5. The only item added was one taco. Drinks cost $2 each.
4 0
2 years ago
John and Belinda played a nine holes of golf. John's score was 10 less than two times Belinda's score. If Johns score was 54 str
polet [3.4K]

Answer:

Belinda's score is 32 strokes.

Step-by-step explanation:

Let the score of John be "x" and Belinda be "y".

It is given that, in the game of golf, John's score was 10 less than two times Belinda's score.

Also, John's score is 54 strokes.

The above equation can be written as ;

x = 2(y) -10

Here, x = 54,

54 = 2(y) -10

64 = 2(y)

y = 32

Thus, Belinda's score is 32 strokes.

6 0
2 years ago
1) Proiectiile catetelor unui triunghi dreptunghic pe ipotenuza au lungimile 9 cm si 25 cm. Aflati lungimea inaltimii din varful
Flauer [41]

Answer:

1) 15cm

2) left projection/h = h/right projection

Step-by-step explanation:

Question:

1) The projections of the legs of a right triangle on the hypotenuse have lengths of 9 cm and 25 cm. Find the length of the height at the top of the right angle.

2) In a right triangle the length of the hypotenuse is 34 cm, and the lengths of the projections of the legs on the hypotenuse are directly proportional to the numbers 0, (6) and 0.75. Calculate the length of the height corresponding to the hypotenuse.

Solution

1) The length of the height of a right angle triangle is also called the altitude.

Since there are no diagrams in the question, I sent a diagram of the right angle as an attachment to the solution.

The projections of the legs are 25cm and 9cm.

Hence, the longer projection length AD = 25cm and the shorter projection length DB = 9cm

In a right triangle, the altitude (height) drawn from the right angle to the hypotenuse divides the hypotenuse into two segments. The length of the altitude is the

geometric mean of these two segments (the two projections) and it's given by:

left projection/h = h/right projection

AD/h = h/DB

25/h = h/9

Cross multiply

h^2 = 25×9

h =√225 = 15cm

The length of the height at the top of the triangle = 15cm

2) Length of hypotenuse = 34

From the question, the lengths of the projections of the legs on the hypotenuse are directly proportional to the numbers 0, (6) and 0.75.

There is an error with the figures because the sum of the length of the projection of the legs should be equal to the hypotenuse but it isn't in this case.

To calculate the length of the height corresponding to the hypotenuse, we would use the same formula above.

left projection/h = h/right projection

To find each leg using question 1 above, each leg of the triangle is the mean proportional between the hypotenuse and the part of the hypotenuse directly below the leg.

Hypotenuse =34cm

Hyp/leg = leg/part

To find leg y, part for leg y = 25cm

34/y = y/25

y^2 = 34×25 = 850

y = √850 = 29.2cm

To find leg x, part for leg x = 9cm

34/y = y/9

y^2 = 34×9 = 306

y = √306 = 17.5cm

8 0
2 years ago
Susan plans to use 120 feet of fencing to enclose a rectangular area for a garden. Which equation best models the area, y, of th
mina [271]
Well we set the perimeter to 120 feet.
This means that 2x+2y=120
Now we know the area of a rectangle is xy so we have to solve for both x and y in the perimeter equation.

2x=120-2y
x=60-y

2y=120-2x
y=60-x

Now we plug these values into our area equation A=xy to get:
A=(60-y)(60-x)
7 0
2 years ago
Read 2 more answers
A pond forms as water collects in a conical depression of radius a and depth h. Suppose that water flows in at a constant rate k
Scrat [10]

Answer:

a. dV/dt = K - ∝π(3a/πh)^⅔V^⅔

b. V = (hk^3/2)/[(∝^3/2.π^½.(3a))]

The small deviations from the equilibrium gives approximately the same solution, so the equilibrium is stable.

c. πa² ≥ k/∝

Step-by-step explanation:

a.

The rate of volume of water in the pond is calculated by

The rate of water entering - The rate of water leaving the pond.

Given

k = Rate of Water flows in

The surface of the pond and that's where evaporation occurs.

The area of a circle is πr² with ∝ as the coefficient of evaporation.

Rate of volume of water in pond with time = k - ∝πr²

dV/dt = k - ∝πr² ----- equation 1

The volume of the conical pond is calculated by πr²L/3

Where L = height of the cone

L = hr/a where h is the height of water in the pond

So, V = πr²(hr/a)/3

V = πr³h/3a ------ Make r the subject of formula

3aV = πr³h

r³ = 3aV/πh

r = ∛(3aV/πh)

Substitute ∛(3aV/πh) for r in equation 1

dV/dt = k - ∝π(∛(3aV/πh))²

dV/dt = k - ∝π((3aV/πh)^⅓)²

dV/dt = K - ∝π(3aV/πh)^⅔

dV/dt = K - ∝π(3a/πh)^⅔V^⅔

b. Equilibrium depth of water

The equilibrium depth of water is when the differential equation is 0

i.e. dV/dt = K - ∝π(3a/πh)^⅔V^⅔ = 0

k - ∝π(3a/πh)^⅔V^⅔ = 0

∝π(3a/πh)^⅔V^⅔ = k ------ make V the subject of formula

V^⅔ = k/∝π(3a/πh)^⅔ -------- find the 3/2th root of both sides

V^(⅔ * 3/2) = k^3/2 / [∝π(3a/πh)^⅔]^3/2

V = (k^3/2)/[(∝π.π^-⅔(3a/h)^⅔)]^3/2

V = (k^3/2)/[(∝π^⅓(3a/h)^⅔)]^3/2

V = (k^3/2)/[(∝^3/2.π^½.(3a/h))]

V = (hk^3/2)/[(∝^3/2.π^½.(3a))]

The small deviations from the equilibrium gives approximately the same solution, so the equilibrium is stable.

c. Condition that must be satisfied

If we continue adding water to the pond after the rate of water flow becomes 0, the pond will overflow.

i.e. dV/dt = k - ∝πr² but r = a and the rate is now ≤ 0.

So, we have

k - ∝πa² ≤ 0 ---- subtract k from both w

- ∝πa² ≤ -k divide both sides by - ∝

πa² ≥ k/∝

5 0
2 years ago
Other questions:
  • The box which measures 70cm X 36cm X 12cm is to be covered by a canvas. How many meters of canvas of width 80cm would be require
    5·1 answer
  • What is true of the function g(x) = –2x2 + 5? G(x) is the multiplication of g and x. –2x2 +5 is the input of the function. The v
    15·2 answers
  • How many distinct 9-letter words starting with “i” can be formed from the word “committee”?
    13·1 answer
  • g A carload of steel rods has arrived at Cybermatic Construction Company. The car contains 50,000 rods. Claude Ong, manager of Q
    9·1 answer
  • The drama club is selling short-sleeved shirts for $5 each, and long-sleeved shirts for $10 each. They hope to sell all of the s
    8·1 answer
  • Matt looks at the architectural plan of a four-walled room in which the walls meet each other at right angles. The length of one
    6·1 answer
  • What is the volume of a right circular cone that has a height of 11.7meters and a base with a circumference of 9 meters? Round t
    5·1 answer
  • The population of big cats in Africa is increasing at a rate of 5% per year. At the
    5·1 answer
  • Explain why you cannot find the intersection points of the two lines shown below. Give both an algebraic reason and a graphical
    15·1 answer
  • rove the following statement directly from the definition of rational number. The difference of any two rational numbers is a ra
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!