AP Statistics 2017

(Marvins-Underground-K-12) #1
Answer: Bimodal,    somewhat    skewed  to  the left.



  1.      For the graph   of  problem #1, would   you expect  the mean    to  be  larger  than    the median  or  the median  to

    be larger than the mean? Why?
    Answer: It is difficult to predict. The general guideline that the mean is lower than the median for
    distributions that are skewed left applies to smooth unimodal distributions. Bimodal distributions
    don’t necessarily follow that pattern.



  2. The first quartile (Q1) of a dataset is 12 and the third quartile (Q3) is 18. What is the largest value
    above Q3 in the dataset that would not be a potential outlier?
    Answer: Outliers lie more than 1.5 IQRs below Q1 or above Q3. Q3 + 1.5(IQR) = 18 + 1.5(18 – 12)
    = 27. Any value greater than 27 would be an outlier. 27 is the largest value that would not be a
    potential outlier.

  3. A distribution of quiz scores has = 35 and s = 4. Sara got 40. What was her z -score? What
    information does that give you if the distribution is approximately normal?
    Answer :


This    means   that    Sara’s  score   was 1.25    standard    deviations  above   the mean,   which   puts    it  at  the 89.4th
percentile (normalcdf(-100,1.25)).



  1.      In  a   normal  distribution    with    mean    25  and standard    deviation   7,  what    proportion  of  terms   are less

    than 20?




Answer  :    Area   =   0.2389.

(By calculator: normalcdf(-100, 20, 25, 7)=0.2375.  )



  1.      What    are the mean,   median, mode,   and standard    deviation   of  a   standard    normal  curve?



Answer: Mean    =   median  =   mode    =   0.  Standard    deviation   =   1.



  1.      Find    the five-number summary and draw    the modified    box plot    for the following   set of  data:   12, 13,

    13, 14, 16, 17, 20, 28.
    Answer: The five-number summary is [12, 13, 15, 18.5, 28]. 28 is an outlier (anything larger than
    18.5 + 1.5(18.5 – 13) = 26.75 is an outlier by the 1.5(IQR) rule). Since 20 is the largest nonoutlier in



Free download pdf