The following data represent weights in kilograms of maize
harvest from a random sample of 72 experimental
plots on St. Vincent, an island in the Caribbean (Reference:
B. G. F. Springer, Proceedings, Caribbean Food Corps.
Soc., Vol. 10, pp. 147–152). Note: These data are also
available with other software on the Stat Space CD-ROM. For
convenience, the data are presented in increasing order.
7.8, 9.1, 9.5, 10.0, 10.2, 10.5, 11.1, 11.5, 11.7, 11.8, 12.2,
12.2, 12.5, 13.1, 13.5, 13.7, 13.7, 14.0, 14.4, 14.5, 14.6,
15.2, 15.5, 16.0, 16.0, 16.1, 16.5, 17.2, 17.8, 18.2, 19.0,
19.1, 19.3, 19.8, 20.0, 20.2, 20.3, 20.5, 20.9, 21.1, 21.4,
21.8, 22.0, 22.0, 22.4, 22.5, 22.5, 22.8, 22.8, 23.1, 23.1,
23.2, 23.7, 23.8, 23.8, 23.8, 23.8, 24.0, 24.1, 24.1, 24.5,
24.5, 24.9, 25.1, 25.2, 25.5, 26.1, 26.4, 26.5, 26.7, 27.1,
29.5
(a) Find the Q1, Q2 AND Q3.
(b) Find the value of the interquartile range (IQR) and
semi-interquartile range( Semi IQR).
(c) Find the lower and upper limits.
(d) Are there any data values below the lower limit? above the
upper limit? List any suspected outliers. What
might be some explanations for the outliers?
(e) Make a box-and-whisker plot of the data.
(f) Discuss the distribution. Does the lower half of the
distribution show more data spread than the upper half?