Answer: The mean of the data is 433.75, variance of the data is 99667.19 and the standard deviation of the data is 315.7011.
Explanation:
The given data is 900, 35, 500 and 300.
The number of observation is 4.
Formula of mean is,


The formula of variance is given below,



The variance of the data is 99667.19


The standard deviation of the data is 315.7011.
The other information or values of given chart is shown in the attached table.
Answer:
The travel time that separates the top 2.5% of the travel times from the rest is of 91.76 seconds.
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 z-score 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 p-value, we get the probability that the value of the measure is greater than X.
Mean of 80 seconds and a standard deviation of 6 seconds.
This means that 
What travel time separates the top 2.5% of the travel times from the rest?
This is the 100 - 2.5 = 97.5th percentile, which is X when Z has a p-value of 0.975, so X when Z = 1.96.




The travel time that separates the top 2.5% of the travel times from the rest is of 91.76 seconds.
Answer:
A
Step-by-step explanation:
Positive 5 intercept
x then y so -4 then 1