a) We will do independent t test and use t critical value for generating confidence interval.
Because population standard deviations are unknown and we are assuming population variances are equal.
b) Assumptions:
1) Normality
2) Homogeneity of Variances .
From above normality plot and boxplot the data are approximately normally distributed.
Since P value=0.084> 0.05 therefore NOT significant. We can conclude that population variances are equal.
c)
FROM ABOVE TABLE 98% CONFIDENCE INTERVAL FOR where
is population mean for Usual fertilizer and
for slow release
fertilizer.
98% confidence interval is (-6.58805,-4.01195)
d) Null hypothesis H0:
ALTERNATIVE HYPOTHESIS Ha:
alpha=0.02
t= -10.502
df= n1+n2-2= 18
P value=0.00
Since P value <0.02 therefore SIGNIFICANT.
Decision: Reject H0.
Conclusion: We have sufficient evidence to conclude that there is difference in means.
NOTE: As per rule I have done the first four question. Please repost question e along with the above data. Thank You.
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