The system of equations of two unknowns is formulated and solved.
The fraction that satisfies the request is 
, since in 
the negative signs are canceled and the first fraction is obtained.
<span>The median would be preferred over the mean in such scenarios because the median will lessen the impact of the outliers that fall within the "tail" of the skew. Therefore, if a curve is normally distributed, that is to say that data is normally distributed, there will be two tails, each with approximately equal proportions of outliers. Outliers in this case being more extreme numbers, and are based on your determination depending on how you are using the data. If data is skewed there is one tail, and therefore it may be an inaccurate measure of central tendency if you use the mean of the numbers. Thinking of this visually. In positively skewed data where there is a "tail" towards the right and a "peak" towards the left, the median will be placed more in the "peak", whereas the mean will be placed more towards the "tail", making it a poorer measure of central tendency, or the center of the data.</span>
There are 24 possible answers, 6 are correct answers and 18 are incorrect answers. By use of the hypergeometric distribution the probabilities of each possible number of randomly selected correct answers can be found, as follows:
P(0) = 0.1379, P(1) = 0.3819, P(2) = 0.341, P(3) = 0.1213, P(4) = 0.017, P(5) = 0.0008, P(6) = 0.000007.
The expected or mean number of correct answers is found from:
The answer is: 1.4998
From the z-table and at p67 or 0.67 (the decimal values in the table),
Z =0.44
See the attached photo (at the point where 0.6700 appears)
