Assignment.1 solution
January, 16, 2010
MATH 203
2.29
Solution :
(a) From the graph, the approximate percentage of aftershocks measuring
between 1.5 and 2.5 is 6%+14%+19%+15%+11%+8%=73%
(b) From the graph, the approximate percentage of aftershocks measuring
greater than 3 is 3%+2%+1.5%+1.25%+.75%+.5%+.30%=9.3%
The percentages are obtained by reading off the heights of the rectangles
between the points (these give the percentages).
The answer is only
an approximation if the two points do not fall as boundary points of
their respective intervals, since you do not know where the points are
distributed within each interval.
2.37
Solution :
(a) They are not symmetrically distributed, since we can see we have more
observation around 6 while the data mean median and mode are not
the same.
1
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Assignment.1 solution
January, 16, 2010
MATH 203
The mean is 7.3, the median is 6.15, and the modes are 5.5, 7, 10.4 and
14.5. so it’s a mupltimodal. so we can’t say the data are symmetrically
distributed.
(b) As we can see even in the histogram, those large observation are unusual
which made the distribution skewed.
2.59
Solution :
(a) The mean of the data is ¯
x
=
∑
x
n
=
11
.
77
8
= 1
.
4713
(b) The median is the average of the middle two numbers once the data are
arranged in order are:
1.37,1.41,1.42,1.48,1.50,1.51,1.53,1.55
The middle two numbers are 1.48 and 1.50. The median is
1
.
48+1
.
50
2
=
1
.
49
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 Statistics, Standard Deviation, Gobi Desert, Dry Steppe

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