Answer:
a) The mean is 
b) The standard deviation is 
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
The probability a student selected at random takes at least 55.50 minutes to complete the examination equals 0.6915.
This means that when X = 55.5, Z has a pvalue of 1 - 0.6915 = 0.3085. This means that when 
So




The probability a student selected at random takes no more than 71.52 minutes to complete the examination equals 0.8997.
This means that when X = 71.52, Z has a pvalue of 0.8997. This means that when 
So




Since we also have that 





Question
The mean is 
The standard deviation is 
the factor for this expression is 7
Which measure of central tendency best describes this situation:
The number of apples in 2-lb bags?
Solution: The best measure of central tendency to describe the numbers of apples in 2-lb bags is mean. Because the variable under consideration is numeric and probably we would not see outliers in 2-lb bags.
Mean is the defined as the sum of observations divided by the number of observation. The mean takes into account all the observation of the data. Mean is most preferable when the data is numeric and there are no outliers in the data.
Therefore, in the given situation, where we have number of apples in 2-lb bags, the mean will be best to use.
Answer:
714
Step-by-step explanation:
So lets go over what we know.
The bus only goes for 6 hours each day.
So lets just think of a full day as 6 hours.
Each day(6 hours), 4284 passangers ride the bus.
To find passangers per hour, we must divide the total passangers by the total hours.
This is 4284(total passangers) divided by 6(total hours):
4284/6
=
714
So each hour, there are 714 passangers.
Hope this helps!