Step 1 involves you listing out all the ways to multiply to 56, and then adding up those factors. For instance, the first row has 1 and 56 which add to 57 in the third column. The second row has -1 + (-56) = -57. The third row has 2+28 = 30. And so on. The idea is to fill out the table completely with the other ways to have factors of 56 added up. The table is shown in the attached image below.
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Step 2 then uses the table to figure out which pair of factors (of 56) add to -15. This would be -7 and -8. In other words,
-7 plus -8 = -15
-7 times -8 = 56
We have found the right pair of numbers. In the table I have provided, this is shown as the highlighted yellow row.
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Step 3 is then using those pair of numbers found in step 2 to set up the factorization. We would say that x^2-15x+56 factors to (x-7)(x-8). This is the same as (x-8)(x-7) as we can multiply two numbers in any order we want.
Answer:
About 35 trees in a state park are infected with insects
Step-by-step explanation:
we know that
7 out of 190 trees are infected with insects
so
using proportion
Find out about how many of the 950 hemlock trees in a state park are infected with insects
therefore
About 35 trees in a state park are infected with insects
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.