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vivado [14]
2 years ago
9

HELP ASAP! PLS!! The Water Department checks the city water supply on a regular basis for

Mathematics
2 answers:
aleksandr82 [10.1K]2 years ago
8 0

Answer:

B. 95% confident the average concentration of PCBs in the water supply is between 2.9 ppb and 3.5 ppb

Step-by-step explanation:

You are given the total number of samples, the concentration of lead, and the standard deviation. The standard deviation represents how inaccurate the estimation of the concentration of lead in the drinking water. This means that there can only possibly be a 0.3 ppb error in the estimation. 3.2-0.3=2.9, and 3.2+0.3=3.5

Mazyrski [523]2 years ago
7 0

Answer:

99.7% confident the average concentration of PCBs in the water supply is between 2.3 parts per billion and 4.1 parts per billion.

Step-by-step explanation:

Just took the question, this is the correct answer.

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Mac earns 4927 bimonthly. how much does he earn per year
NISA [10]
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I think you need to do 2927x24

7 0
3 years ago
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What is the gcf for 14 and 55?
pentagon [3]
The greatest common factor would be 1 because you need to factor both 14 and 55 so factor 14 and you get 2 and 7 factor 55 you get 5 and 11 the the GCF has to be 1
I hope this is helpful
4 0
3 years ago
A unit rate is a rate in which the _ in the comparison is 1 unit.
Nikitich [7]

Answer:

3.1415967382

Step-by-step explanation:

7 0
3 years ago
A circle has its center at (0,0) and passes through the point (0,9). What is the standard equation of the circle?
Alexxandr [17]

Answer:

x^2+y^2=9^2

Step-by-step explanation:

The standard equation of a circle is:

(x-h)^2+(y-k)^2=r^2

Where the center of a circle is (h,k) and r is the radius of the circle.  In this case because a circle is equidistant from the center and we have a point where it passes through 9 that means that the radius is 9.  However, since the standard equation states that we must write r in the form of r^2 this means that r^2=9^2.  Therefore by plugging in the values we have:

(x-0)^2+(y-0)^2=9^2\\\\x^2+y^2=9^2

7 0
2 years ago
Rewrite the equation by completing the square.<br> x^2 + 2x – 48 = 0
slamgirl [31]

Answer:

(x+1)^2 = 49

x = 6                 x = -8

Step-by-step explanation:

x^2 + 2x – 48 = 0

Add 48 to each side

x^2 + 2x =48

Take the coefficient of x

2

Divide by 2

2/2=1

Square it

1^2 =1

x^2 + 2x +1=48+1

x^2 +2x+1 = 49

(x+1)^2 = 49

Take the square root of each side

sqrt((x+1)^2) =±sqrt( 49)

x+1 = ±7

Subtract 1 from each side

x+1-1 = -1  ±7

x = -1+7          x = -1 -7

x = 6                 x = -8

3 0
3 years ago
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