Question

The two dot plots below show the heights of some sixth graders and some seventh graders:

Two dot plots are shown one below the other. The title for the top dot plot is Sixth Graders and the title for the bottom plot is Seventh Graders. Below the line for each dot plot is written Height followed by inches in parentheses. There are markings from 52 to 57 on the top line and the bottom line at intervals of one. For the top line there are 2 dots above the first mark, 1 dot above the second mark, 1 dot above the third mark and 2 dots above the fourth mark. For the bottom line, there are 2 dots for the fifth mark, there are 4 dots above the sixth mark.

The mean absolute deviation (MAD) for the first set of data is 1.2 and the MAD for the second set of data is 0.4. Approximately how many times the variability in the heights of the seventh graders is the variability in the heights of the sixth graders? (Round all values to the tenths place.)

3.2
3.0
1.5
0.8

Answer 1

answer = 3.0
hope this helped! 

Answer 2

Answer:

The answer is:

3

Step-by-step explanation:

There are total 6 dots.

This means that the sample population is: 6

We are given mean absolute deviation for the first set i.e. sixth graders of data as:

                          1.2

This means that the variance of data is:

σ=1.2/6

Similarly the means absolute deviation for the second set i.e. seventh graders of data is:

                         0.4

This means that the variance of data is:

σ'=0.4/6

Let 'n' denote the number of  times the variability in the heights of the seventh graders is the variability in the heights of the sixth graders.

This means that:

                                 σ=6σ'

i.e. $\dfrac{1.2}{6}=n\times \dfrac{0.4}{6}\\\\\\1.2=n\times 0.4\\\\i.e.\\\\n=\dfrac{1.2}{0.4}\\\\n=\dfrac{12}{4}\\\\n=3$

Hence, the answer is:

                       3