Plugging the values if x and y the last option is correct
3x-y=4
Answer:
a)
b) 
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 weights 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 like this:
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
Part b
For this case we select a sample size of n =32. Since the distribution for X is normal then the distribution for the sample mean
is given by:
And the new z score would be:



Answer: Tammy's sample may not be vaild because she surveyed the students only from her class and it is likely that other classes might not like the subject maths. She might get the accurate results by surveying a larger number of people in the school instead of just her class.
Answer:
B. -3, -10, -17, -24, -31
Step-by-step explanation:
An Arithmetic sequence is defined as a set of numbers with a common difference. In answer choice B, it is seen that the difference between each number is seven.
A is incorrect as one to eight has a difference of seven, while the other numbers have a difference of eight.
C is incorrect as it skips the number 12 between 9 and 15, thus breaking the sequence.
D is incorrect as the numbers jump from positive to negative, thus not having a common difference.
Hope this helps!
-1/3
Use the formula m = y2-y1/ x2 - x1.
Substitute the x and y values and you'll get -1/3