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Velvetleaf is a particularly annoying weed in corn fields. It produces lots of s

ID: 3176685 • Letter: V

Question

Velvetleaf is a particularly annoying weed in corn fields. It produces lots of seeds, and the seeds wait in the soil for years until conditions are right. The velvetleaf seed beetle feeds on the seeds and might be a natural weed control. Here are the percent of seeds infected for 14 randomly selected velvetleaf plants:

For the beetle to be successful at Velvetleaf weed control, they need to infect more than 5.0% of the seeds on average.

SD is 2.03

What is the test statistic and p-value?

Percent Infected 5.2 5.5 6.1 5.7 2.3 0.5 0.7 5.1 4.7 9.3 8.1 7.3 6.6 5.2

Explanation / Answer

from above

std deviation from above =2.5379

std error=2.5379/sqrt(14)=0.6783

test stat z=(X-mean)/std error

=(5.164-5)/0.6783=0.2422

for which p value=0.4062

hence p value are 0.25 to 0.5

X 5.200 5.500 6.100 5.700 2.300 0.500 0.700 5.100 4.700 9.300 8.100 7.300 6.600 5.200 mean(X) 5.164

std deviation from above =2.5379

std error=2.5379/sqrt(14)=0.6783

test stat z=(X-mean)/std error

=(5.164-5)/0.6783=0.2422

for which p value=0.4062

hence p value are 0.25 to 0.5