Question

The test scores of 32 students are listed below. Construct a boxplot for the data set and include the values of the 5-number summary. 32 37 41 44 46 48 53 55 57 57 59 63 65 66 68 69 70 71 74 74 75 77 78 79 81 82 83 86 89 92 95 99

Answer 1

Answer:

Boxplot is constructed using quartiles and 5 No. summary means including minimum value of data, 1st quartile, 2nd quartile, 3rd quartile and maximum value of data.

As data already in increasing order, we find quartiles using the following formula,

$value\:of\:K_{th}\:Quartile\:,\, Q_k=\:value\:of\:(\frac{k\times{(n+1)}}{4})\,\:th\,observation$

where n = No. of Observations.

∴, 1st Quartile,

$Q_1 = \frac{1\times{(32+1)}}{4}\, th\:\:observation\\\\ \:\:\:=8.25\,th\:observation\\\: \:\:= 8th\,+0.25(9th-8th)\\\:\:\:= 55 + 0.25(57-55)\\\:\:\:= 55.5$

2nd Quartile,

$Q_2 = \frac{2\times{(32+1)}}{4}\, th\:\:observation\\\\ \:\:\:=16.5\,th\:observation\\\: \:\:= 16th\,+0.5(17th-16th)\\\:\:\:= 69 + 0.5(70-69)\\\:\:\:= 69.5$

3rd Quartile,

$Q_3 = \frac{3\times{(32+1)}}{4}\, th\:\:observation\\\\ \:\:\:=24.75\,th\:observation\\\: \:\:= 24th\,+0.75(25th-24th)\\\:\:\:= 79 + 0.75(81-79)\\\:\:\:= 80.5$

Minimum value of data = 32 & Maximum value of data = 99

So, Values of 5 no. that are to ne include in Boxplot are 32, 55.5, 69.5, 80.5, 99.

BoxPlot is attached with this ans.