When seven times a number is decreased by 66 the result is 50. what is the number?
1 answer:
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Answer:
And we can solve this using the following z score formula:
And if we use this formula we got:
So we can find this probability equivalently like this:
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 heights of a population, and for this case we know the distribution for X is given by:
Where and
We select n =100. Since the distribution for X is normal then we know that the distribution for the sample mean is given by:
We want this probability:
And we can solve this using the following z score formula:
And if we use this formula we got:
So we can find this probability equivalently like this: