4. Jane owns 11 times as many books as Mike.
1 answer:
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Answer:
I don’t know which answer choice it is since C and D are the same but the answer is supposed to be x < -15.
Step-by-step explanation:
the image has the work shown
Calculate the value of z and its probability, since with this we can know how likely it is that this will happen.
We have that the mean (m) is equal to 8.3, the standard deviation (sd) 1.2 and the sample size (n) = 15
They ask us for P (x =7.2)
For this, the first thing is to calculate z, which is given by the following equation:
z = (x - m) / (sd / (n ^ 1/2))
We have all these values, replacing we have:
z = (7.2 - 8.3) / (1.2 / (15 ^ (1/2))
z = -3.55
With the normal distribution table (attached), we have that at that value the approximate probability is:
P (z = -3.55) = 0.0001
The probability is 0.01 %
This affirms that the students do not sleep what the study says because the probability of this happening according to the survey is almost nil.
It is pretty easy to eliminate the wrong answers by trying the answers in the equations.
a. 7 times 30 is way more than 4
c. 6 times 226 is way more than 172, even after subtracting 64
d. 7 times -74 is way less than 4
The appropriate choice is
... b. x=4, y=30
You can check it with your graphing calculator.
_____
Since you have an expression for y, you can substitute that into the second equation:
... -2x + 6(2+7x) = 172 . . . . substitute for y
... 40x = 160 . . . . . . . . . . . . eliminate parentheses, subtract 12, collect terms
... x = 4 . . . . . . this is sufficient to help you locate the correct answer
