Question

9. Calculate the standard deviation of the class count data. For full credit you must show all of your work. The standard deviation should be no more than two significant figures. (15 pts) SD = . Sxa-)3 1-1 Write the meant standard deviation: L(2pts) Write the range of the standard deviation about the mean (3pts) 10. How precise were the counts? Explain using the standard deviation calculated. How does sample size contribute to a smaller standard deviation? (Spts) 11. Use graph paper: create a bar graph of the frequency of occurrence of chromosomes counted. Include a title, label x and y axes. Draw a vertical dashed line to the mean number of chromosomes. label the mean (x) above the line. (20pts) Draw horizontal arrows to each standard deviation point (plus and minus) and a solid vertical line to the corresponding chromosome numbers on the x axis. (10pts).

Answer 1

Mean = sum of all data points / totl number of data points = 150/10 = 15

n	xo	[xo-x-]	(xo- x-)2
1	13	2	4
2	15	0	0
3	16	1	1
4	15	0	0
5	17	2	4
6	14	1	1
7	16	1	1
8	12	3	9
9	16	1	1
10	16	1	1
	150		22

standard deviation = root of ( $\sum$ ( xo-x-)2 / n - 1)

= 1.56

mean +/- SD = 15 +/- 1.56

range of standard deviation about the mean = max - min / 4 = 9- 1/4 = 2