the dormancy enhancing plant hormone known as ABA( abscissic acid) has been note
ID: 3150681 • Letter: T
Question
the dormancy enhancing plant hormone known as ABA( abscissic acid) has been noted to retard seed germination in all standard crop seeds(eg corn, bean,pea etc) used.However, you decide to test its effectiveness on natural vegetation. You collect several dozens of mature seeds from the savanna plant knows as Golden Alexanders.The seeds are randomly split into two groups. Both groups are placed in separate petri dishes lined with filter paper. in one dish you pipette 8.0 ml of distilled water while the other dish received 8.0 ml of a 1.5mg/1 ABA solution. After three days in a dark box, both groups were examined for seed germination with the following results .
Treatment
#seed germinated
N
%germination
Water(control)
54
63
.857142857 or
85.7142857%
ABA(experiment)
44
63
0.698412698 or 69.8412698%
a) calculate the 95% confidence interval for the percentage(proportion) of seeds that germinated for the ABA-treated seeds using the three techniques below. Remember, Z=1.960
i)standard method ii) wilson method iii)safe/conservative method
b)Calculate the 95% confidence interval for the difference in percentages of seeds that germinated for the two treatments using the standard method AND INTERPRET THIS CONFIDENCE INTERVAL. remember z=1.960
c)Repeat problem b above but now use the safe/conservative method- interpret your confidence interval. Remember, Z=1.960
Treatment
#seed germinated
N
%germination
Water(control)
54
63
.857142857 or
85.7142857%
ABA(experiment)
44
63
0.698412698 or 69.8412698%
Explanation / Answer
a.
i.standard method
Confidence Interval for Diffrence of Proportion
CI = (p1 - p2) ± Z a/2 Sqrt(p1(1-p1)/n1 + p2(1-p2)/n2 )
Proportion 1
No. of chances( X1 )=54
No.Of Observed (n1)=63
P1= X1/n1=0.857
Proportion 2
No. of chances(X2)=44
No.Of Observed (n2)=63
P2= X2/n2=0.698
C.I = (0.857-0.698) ±Z a/2 * Sqrt( (0.857*0.143/63) + (0.698*0.302/63) )
=(0.857-0.698) ± 1.96* Sqrt(0.005)
=0.159-0.143,0.159+0.143
=[0.016,0.301]
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