1answer.
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
vekshin1
3 years ago
11

On any given day, the probability that a large local river is polluted by carbon tetrachloride is 0.12. Each day, a test is cond

ucted to determine whether the river is polluted by carbon tetrachloride. This test has proved correct 84 percent of the time.1. What proportion of days does the test indicate carbon tetrachloride pollution? 2. Suppose that on a particular day the test indicated carbon tetrachloride pollution What is the probability that such pollution actually exists? 3. What percentage of days where the test is negative will the river actually be polluted?
Mathematics
1 answer:
babymother [125]3 years ago
4 0

Answer:

a) 0.2416

b) 0.4172

c) 0.0253

Step-by-step explanation:

Since the result of the test should be independent of the time , then the that the test number of times that test proves correct is independent of the days the river is correct .

denoting event a A=the test proves correct and B=the river is polluted

a) the test indicates pollution when

- the river is polluted and the test is correct

- the river is not polluted and the test fails

then

P(test indicates pollution)= P(A)*P(B)+ (1-P(A))*(1-P(B)) = 0.12*0.84+0.88*0.16 = 0.2416

b) according to Bayes

P(A∩B)= P(A/B)*P(B) → P(A/B)=P(A∩B)/P(B)

then

P(pollution exists/test indicates pollution)=P(A∩B)/P(B) = 0.84*0.12 / 0.2416 = 0.4172

c) since

P(test indicates no pollution)= P(A)*(1-P(B))+ (1-P(A))*P(B) = 0.84*0.88+  0.16*0.12 = 0.7584

the rate of false positives is

P(river is polluted/test indicates no pollution) = 0.12*0.16 / 0.7584 = 0.0253

You might be interested in
PLEASE HELP I think is A or D
Natalka [10]
Looking at the angles of the triangles

N=S
M=R
O=T

so MON would be RTS
5 0
3 years ago
I need to find the resultant matrix
fomenos

the answers are there

i hope it will help you

7 0
3 years ago
Brian correctly use a method of completing the square to solve the equation X a 2nd plus 7X -11 equals zero Brian‘s first step w
ArbitrLikvidat [17]

Answer:

(\frac{7}{2})^{2}

Step-by-step explanation:

Brain correctly use a method of completing the square to solve the equation:

x^2+7x-11=0

His First Step is to: Take the Constant Term to the Right Hand Side

x^2+7x=11

The Next Step Would be to:

  • Divide the Coefficient of x by 2
  • Square It
  • Add it to both Sides

In this case, the Coefficient of x  = 7

  • Divided by 2 = \frac{7}{2}
  • Squaring It, we have: (\frac{7}{2})^{2}

It is this number (\frac{7}{2})^{2} that is added to both sides in the manner below:

x^2+7x+(\frac{7}{2})^{2}=11+(\frac{7}{2})^{2}

6 0
3 years ago
What is 4/5 divided 1/3
vova2212 [387]
The answer would be 2.4, or in fraction form 12/5. Please mark brainliest <3
5 0
2 years ago
Read 2 more answers
Can u help me in this <br> plz plz
e-lub [12.9K]

3. A square is a rhombus in which all the angles equal (to 90°).

4. 20 : 24 ratio that the ball picked wont be green

5. false

11. 15

12. half a chance (1/2)

13. 51

16. 9.79 × 10^-5

17. 4y = 29

18. b) 6.1

19. 80

20. x = -8/7

30. Area ≈ 7982.79

34. check the picture i attached for the histogram

THIS TOOK SO LONG

7 0
3 years ago
Other questions:
  • If a study determines the difference in average salary for subpopulations of people with blue eyes and people with brown eyes is
    13·1 answer
  • If you wanted an output of 7 for the rule y = -x + 4, what would you need as an input?
    15·1 answer
  • Your brother is going to buy a car when he graduates, but he doesn't have enough money to pay for it in cash. He takes a loan ou
    9·1 answer
  • A map shows the road between the cities of Saxon and Melbeck. If the distance on the map between the two cities is 7 inches, wha
    10·1 answer
  • What value of x is in the solution set of 8x – 6 &gt; 12 + 2x?<br> (answer choices are -1, 0, 3, 5)
    10·1 answer
  • In the figure AB = BC = CD = DA 2 3.2 units. The slope of AB is. What else do
    7·1 answer
  • A single batch of cookies requires two cups of sugar and three cups of flour. If more than one batch or a partial batch was made
    15·2 answers
  • Can someone please help? will give brainliest
    11·2 answers
  • What is the solution for x? x/5=2
    13·2 answers
  • Find the lcm of polynomials (x³-4x²+4x) and (2x²-3x-2)<br><br><br><br>I need this answer fast​
    14·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!