The Basics...

#1
Parking at a large school has become a very big problem. Administration is interested in determining the average parking time of its students. An administrator inconspicuously followed a random sample of 150 students and carefully recorded their parking times. The average of these students parking times was observed to be 3 minutes while the median parking time was 1.2 minutes.

1. Identify the population, sample, and variable of interest to the administrators. 2. Do the parking times follow a left skewed distribution?
3. If Σ X^2 = 1400, then what is the sample variance?
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1. I guess the sample is 150. But I don't know the other two?
2. Do I have to graph this? I think I need the info from part 1 do answer this one.
3. Is the sample variance the square root of 1400? I guess we don't need the info from the other parts to answer this one. I got 37.42 rounded.

Can anyone assist with this one? Thanks folks!
 

JohnM

TS Contributor
#2
1. the sample is the 150 parking times that were measured - the population is all of the parking times - the variable is the time measured in minutes

2. skewness can be determined by knowing the relative positions of the mean and median - hint: a skewed distribution will "pull" the mean away from the median, in the direction of skew

3. carefully examine the formula for sample variance - you have enough information to compute it......