# TUTORIAL EXERCISE PACKAGE - 2010 Math1015 - Biostatistics Semester by lindayy

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```									                                   TUTORIAL EXERCISE PACKAGE - 2010
Math1015 - Biostatistics

Semester 1                                                   Tutorial Week 2                                                       2010

We encourage you to attempt these problems before your tutorial class.
¯
Make sure you know how to ﬁnd x and s using the STAT mode of your calculator.

Students are now allowed to take their own calculators into the examination room,
as long as they are from the approved list of calculators. See course web page for more details.

If possible, give your answers to at least two dp.

1. Seven observations from an experiment are x1 = −2.0, x2 = 0.0, x3 = 4.5, x4 = 1.8, x5 = 3.0, x6 =
5.2, x7 = 8.0. ﬁnd
7                           7                                          7
(a) x =
¯            xi /7         (b)           x2
i                        (c) s2 =         (xi − x)2 /6
¯
i=1                       i=1                                          i=1

Check your answers using the STAT mode of your calculator.

2. (Multiple choice) Consider the following table for i and xi values:
i 1 2 3 4 5
xi 1 6 8 4 6
The variance of x for the data is (2dp):
(a) 5.60                 (b) 8.70                        (c) 10.4                 (d) 7.00                   (e) none of the above.

3. Consider the following data set consisting of 12 observations:
0.7     1.1       0.7    0.9    6.5   1.6    4.0   29.1      0.2   0.1    9.2   11.9
Rearrange the data in ascending order.

4. Find the median and quartiles for the data in Q3. Draw a boxplot of these data.

Use R to answer these questions.

5. A sample of 24 mice was used to investigate the use of iron as a dietary supplement. The percentage
of iron retained were
7.3      1.2       4.9    5.7    13.0 1.0 3.7 0.2 10.8                1.0     2.4 12.8
1.4     14.4       1.8    9.9     3.4 3.8 9.9 4.1 4.1                23.0    21.0 12.9
(a) Find the mean, variance and standard deviation of this data set.
(b) Produce a stem-and-leaf display of the data.
(c) Comment on the shape of the distribution.

6. Draw a boxplot the data in Q5.
TUTORIAL EXERCISE PACKAGE - 2010
Math1015 - Biostatistics

Semester 1                                    Problem Sheet Week 2                                                    2010

We encourage you to do these further problems in order to understand the course material well. Lecturers and tutors are
available during their oﬃce hours for help.

1. Find the IQR, LT, and UT for the data in Q5 and identify any outliers.
(Remember: LT= LQ-1.5(IQR); UQ=UQ+1.5(IQR))

2. (Refer to data in Q5, tutorial section) Find the propotion of observations lie within (¯ − 2s, x + 2s).
x       ¯

3. Using R draw a histogram with 8 classes for the data in Q5.

We recommend these Extra problems from Fundamentals of Biostatistics Ch 2
p.37-42 Q2.13 to 2.18.

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