Jose needs to memorize words on a vocabulary list for French class. He has memorized 20 of the words, which is four-fifths of th
1 answer:
Answer:
25
Explanation:
In order to solve this the easiest way you can use equivalent fractions.
Since 4 times 5 equals 20 we can multiply 5 times 5 to get our answer.
25 is the answer. But, if we couldn't have gotten to 20 through the multiplication we could use a proportion. That would look like the initial problem but instead of a "?" we would use a variable. I will use <em>t</em> for total.
So now we have our problem set up. The next step is to cross multiply. 4 by <em>t</em> and 5 by 20.
And now we can solve it like a normal algebra problem.
Either way, we get 25.
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Answer:
a)
b)
c)
d)
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".
Part a
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 a random sample of n=36. And from the central limit theorem we know that the distribution for the sample is given by:
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:
Part b
For this case we want this probability:
And we can find this probability on this way:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
Part c
If we apply this formula to our probability we got this:
Part d
For this case we want this probability:
And we can find this probability on this way:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.