Five years ago, John’s age was half of the age he will be in 8 years. How old is he now?
1 answer:
You might be interested in
Answer:
And we can find this probability using the complement rule:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
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 scores of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the complement rule:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
Answer:
Step-by-step explanation:
Remember that we evaluate the term under the radical first.
Even though x < 0, x²² > 0
So,
The simplified expression is