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marta [7]
3 years ago
10

contaminants such as trihalomethanes (THMs). The Water Department takes 200 samples and estimates that the concentration of THMs

in your drinking water is 3.5 ppb (parts per billion), with a standard deviation of 0.2 ppb. Assuming the samples were random and unbiased, how much confidence can you have in this data?
Mathematics
1 answer:
andrew11 [14]3 years ago
7 0

Answer:

idk

Step-by-step explanation:

You might be interested in
In a certain clothing store, 4 shirts and 6 ties cost $70, and 2 shirts and 4 ties cost $42. What is the cost of each tie?
Oksanka [162]

Answer:

  $7

Step-by-step explanation:

Your two equations are ...

  • 4s +6t = 70
  • 2s +4t = 42

Double the second equation and subtract the first:

  2(2s +4t) -(4s +6t) = 2(42) -(70)

  2t = 14 . . . . . simplify

  t = 7 . . . . . . . divide by 2

The cost of each tie is $7.

3 0
4 years ago
Factor p^4-81 completely showing all work.
3241004551 [841]

Answer:

Step-by-step explanation:

p^4-81=(p^2)^2-9^2=(p^2+9)(p^2-9)=(p^2-9(-1))(p+3)(p-3)\\=(p^2-9i^2)(p+3)(p-3)\\=(p+3i)(p-3i)(p+3)(p-3)

8 0
3 years ago
PLEASE HELP ASAP!!!!!
wariber [46]

the answer to this would be C I hope this helps :)

4 0
3 years ago
g If the economy improves, a certain stock stock will have a return of 23.4 percent. If the economy declines, the stock will hav
dusya [7]

Answer:

E(X) = 23.4* 0.67 -11.9*0.33= 11.759 \%

Now we can find the second central moment with this formula:

E(X^2) = \sum_{i=1}^n X^2_i P(X_i)

And replacing we got:

E(X^2) = (23.4)^2* 0.67 +(-11.9)^2*0.33= 413.5965

And the variance is given by:

Var(X) = E(X^2) - [E(X)]^2

And replacing we got:

Var(X) = 413.5965 -(11.759)^2 =275.5105

And finally the deviation would be:

Sd(X) = \sqrt{275.5105}= 16.599 \%

Step-by-step explanation:

We can define the random variable of interest X as the return from a stock and we know the following conditions:

X_1 = 23.4 , P(X_1) =0.67 represent the result if the economy improves

X_2 = -11.9 , P(X_1) =0.33 represent the result if we have a recession

We want to find the standard deviation for the returns on the stock. We need to begin finding the mean with this formula:

E(X) = \sum_{i=1}^n X_i P(X_i)

And replacing the data given we got:

E(X) = 23.4* 0.67 -11.9*0.33= 11.759 \%

Now we can find the second central moment with this formula:

E(X^2) = \sum_{i=1}^n X^2_i P(X_i)

And replacing we got:

E(X^2) = (23.4)^2* 0.67 +(-11.9)^2*0.33= 413.5965

And the variance is given by:

Var(X) = E(X^2) - [E(X)]^2

And replacing we got:

Var(X) = 413.5965 -(11.759)^2 =275.5105

And finally the deviation would be:

Sd(X) = \sqrt{275.5105}= 16.599 \%

7 0
3 years ago
What is the answer for b, and why?
kkurt [141]
I think it will be 125
7 0
3 years ago
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