1. MTH3401
PROBABILITY AND STATISTICS 1
SEM 1 2021/2022
Student Centered Learning (SCL)
Topic: Introduction to statistics and data analysis
This is a group assignment comprising of about 5 students in each group and the latest
day of submission of the assignment (Softcopy) in PutraBlast is 10 November 2021.
Data description:
The data shown is a U.S. Army Corps of engineering data on fish contaminated from the
toxic discharges of a chemical plant located on the banks of the Tennessee River in
Alabama. The engineer determined the species (channel catfish, largemouth bass, or
smallmouth buffalo fish) for each of the 143 captured fish. The engineer also recorded the
length (in centimeters), weight (in grams) and DDT level (in parts per million) for the 143
fishes. The data on species are saved in the DDT file.
Questions:
1. By using the DDT level,
(a) determine three numerical measures of central tendency for the 143 DDT level.
Interpret these values.
(b) construct a stem-and-leaf plot.
(c) construct a dot plot with three species (CCATFISH, SMBUFFALO and LMBASS) on
the same graph and identify three means (i.e., mean DDT level for CCATFISH, mean
DDT level for SMBUFFALO and mean DDT level for LMBASS)
(d) based on the graphical result in question 1(c), comment on the influence of species for
DDT level. Take into account the position of the three means and variability around
each mean.
2. By using the fish weights,
(a) calculate the values of the three quartiles and the interquartile range. Where does the
value 1000 fall in relation to these quartiles?
(b) construct a boxplot for fish weights. Comment on the skewness.
3. By using the fish lengths,
(a) Set up a relative frequency distribution. Use the classes 15.0-19.9, 20.0-24.9, …
(b) Construct a relative frequency histogram.
(c) By referring to relative frequency table constructed in question 3(a), determine
(i) mean
(ii) median
(iii) mode
(iv) standard deviation
