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Calculate Jean's rate
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Jean takes 8 hours to fill the pool.
So in 1 hour, she can fill 1/8 of the pool

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Calculate Mark's rate
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Mark takes 12 hours to fill the pool.
So in 1 hour, he can fill 1/12 of the pool.

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Calculate their rate if they work together
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Jean = 1/8
Mark = 1/12
1/8 + 1/12 = 3/24 + 2/24 = 5/24
They will fill 5/24 of the pool in 1 hour

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Find number of hours needed to fill up the pool
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I hour = 5/24 of the pool
1 ÷ 5/24 hour = 5/24 ÷ 5/24 of the pool
24/5 hour = Whole pool

Whole pool = 24/5 hours
Whole pool = 4 4/5 hours or 4.8 hours

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Ans: The supervisor is not correct, it will take only 4.8 hours if both of them work together.
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5 0

3 years ago

If IQ scores are normally distributed with a mean of 100 and a standard deviation of 15, what is the mean IQ score after the sco

lianna [129]

Answer:

$\mu = 0 , \sigma=1$

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Solution to the problem

Let X the random variable that represent the IQ scores of a population, and for this case we know the distribution for X is given by:

$X \sim N(100,15)$