Question

An intelligence test that has a maximum completion time of 45 minutes was recently administered to a group of 9 people. Their respective completion times (in minutes) were as follows: 45, 40, 42, 39, 44, 40, 45, 33, 31 / 25 to Excel (a) What is the mean of this data set? If your answer is not an integer, round your answer to one decimal place. (b) What is the median of this data set? If your answer is not an integer, round your answer to one decimal place. (c) How many modes does the data set have, and what are their values? Indicate the number of modes by clicking in the appropriate circle, and then indicate the value(s) of the mode(s), if applicable. zero modes one mode two modes:and Clear Undo Help Next Question >>

Answer 1

Answer:

a) $\bar X=39.9$

b) Median =40

c) Bimodal distribution 40,45 with a frequency of 2 for each one

Step-by-step explanation:

Part a

The statistical mean refers "to the mean or average that is used to derive the central tendency of the data in question. It is determined by adding all the data points in a population and then dividing the total by the number of points". And is defined:

$\bar X =\frac{\sum_{i=1}^n x_i}{n}$

And for this case if we apply this formula we got:

$\bar X =\frac{45+40+42+39+44+40+45+33+21}{9}=39.9$

Part b

The median is a "measure of central tendency. To find the median, we arrange the observations in order from smallest to largest value. And we have two possible cases:

1) If there is an odd number of observations, the median is the middle value. 2) If there is an even number of observations, the median is the average of the two middle values."

So if we order the dataset we got:

31,33,39,40,40,42,44,45,45

Since we have an odd number of observation n=9, the median would be just the middle value on position 5 and for this case Median =40

Part c

The mode of a set of data values is the value that appears most often. As a set of data can have more than one mode, the mode does not necessarily indicate the centre of a data set.

For this case we have a bimodal distribution and the corresponding values are 40 and 45 with a frequency of 2 for each one.