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Tcecarenko [31]
3 years ago
11

A neuroscientist measures the reaction times (in seconds) during an experimental session in a sample of cocaine-addicted (n = 8)

, morphine-addicted (n = 12), and heroin-addicted rats (n = 6). Mean reaction times in each sample were 11, 18, and 13 seconds, respectively. What is the weighted mean for all three samples? Hint: The overall mean is not 14.0 seconds. (Round your answer to two decimal places.)
Mathematics
1 answer:
Marysya12 [62]3 years ago
8 0

Answer:

14.69 seconds

Step-by-step explanation:

The weighted mean is used to calculate the mean of numbers which don't have the same "weight" or statistical relevance. In this case, that relevance is based on the sample size of each group from which the mean reaction times were obtained.

For all three samples, the weighted mean is obtaining by multiplying each one of the mean reaction times by its <em>n value, </em>adding them, and dividing that result by the sum of all n values.

WM=\frac{11*8+18*12+13*6}{8+12+6} =14.69\\

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valentina_108 [34]

Answer:

Solving the equation x^2+6x-8=0 by completing the square method we get \mathbf{(x+3)^2=17}

Option B is correct option.

Step-by-step explanation:

We need to solve the equation x^2+6x-8=0 by completing the square method.

For completing the square method: we need to follow: a^2+2ab+b^2=(a+b)^2

We are given:

x^2+6x-8=0

Solving by completing the square

x^2+2(x)(?)+(?)^2-8=0

We need to find ? in our case ? is 3 because 2*3= 6 and our middle term is 6x i,e 2(x)(3)=6x.

So, adding and subtracting (3)^2

x^2+2(x)(3)+(3)^2-8-(3)^2=0\\(x+3)^2-8-9=0\\(x+3)^2-17=0\\(x+3)^2=17

So, solving the equation x^2+6x-8=0 by completing the square method we get \mathbf{(x+3)^2=17}

Option B is correct option.

7 0
2 years ago
WILL MARK BRAINLEST <br> PLS SHOW STEP BY STEP
defon

Answer:

\frac{225}{30} or 7\frac{1}{2}

Step-by-step explanation:

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Answer:

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Step-by-step explanation:

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