Incomes of workers in an automobile company in Michigan are known to be right - skewed with a mean equal to $36,100. If at least 8/9 of all incomes are in the range of $29,600 to $42,800, and this was based on Chebyshev's Theorem, what is the standard deviation for the auto workers?
a) $6,500 b) $6,700 c) Approximately $4,755 d) $2,200

Respuesta :

Answer: a) $6,500

Step-by-step explanation:

According to the Chebyshev's Theorem , about [tex](1-\dfrac{1}{k^2})[/tex] of the values from a data set will wall k standard deviation from mean .

As per given , we have

At least 8/9 of all incomes are in the range of $29,600 to $42,800.

[tex]\mu=\dfrac{\text{Sum of limits}}{2}=\dfrac{29600+42800}{2}=36200[/tex]

i.e.  [tex](1-\dfrac{1}{k^2})=\dfrac{8}{9}[/tex]

[tex]\dfrac{1}{k^2}=1-\dfrac{8}{9}=\dfrac{1}{9}[/tex]

[tex]k^2=9\\\\ k=\pm 3[/tex]

Now in range , lower limit = Mean - k (Standard deviation) = $29,600

⇒ $36,200 - (3)(Standard deviation)= $29,600

⇒ (3)(Standard deviation)= $36,200-$29,600 = $ 6600

⇒ Standard deviation= ( $6600) ÷3 = 2200

Hence, the standard deviation for the auto workers is $6,500.

Thus , the correct answer is a) $6,500 .

It can be deduced that the standard deviation for the auto workers is $2200.

How to calculate the standard deviation

From the information given, it can be noted that:

P (29600 < x < 42800) > 8/9

where, x = random variable

By Chebyshev's Theorem, we will have:

k = 3

Mean = 29600

(u + 3sd) - (u - 3sd) = 42800 - 29600

6sd = 13200

SD = 13200/6

SD = $2200

In conclusion, the standard deviation is $2200.

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