Ask Question
27 October, 01:22

A neuroscientist measures the reaction times (in seconds) during an experimental session in a sample of cocaine-addicted (n = 8), morphine-addicted (n = 6), and heroin-addicted rats (n = 12). Mean reaction times in each sample were 12, 13, and 17 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.)

+3
Answers (1)
  1. 27 October, 01:42
    0
    14.54

    Step-by-step explanation:

    In a weighted average a "weight" is associated to each value.

    The weighted mean is computed the following way:

    Suppose you want to calculate the weighted mean of the values

    a1, a1, ..., an

    with weights

    w1, w2, ..., wn

    Then

    Weighted mean = (w1*a1+w2*a2 + ... + wn*an) / (w1+w2 + ... + wn)

    In this case we have

    a1 = 12, w1 = 8

    a2 = 13, w2 = 6

    a3 = 17, w3 = 12

    Weighted mean

    (12*8+13*6+17*12) / (8+6+12) = 14.54 rounded to 2 decimal places.
Know the Answer?
Not Sure About the Answer?
Find an answer to your question 👍 “A neuroscientist measures the reaction times (in seconds) during an experimental session in a sample of cocaine-addicted (n = 8), ...” in 📗 Mathematics if the answers seem to be not correct or there’s no answer. Try a smart search to find answers to similar questions.
Search for Other Answers