4-part question! We want to determine if taking a vitamin supplement has any eff
ID: 2928866 • Letter: 4
Question
4-part question!
We want to determine if taking a vitamin supplement has any effect on lifespan. Some studies have reported that vitamins increase health, but other studies have suggested that vitamins might have detrimental effects. We decide to study the effects of daily vitamin use on 25 rats. Assume that the lifespans of rats are normally distributed with a mean lifespan of 1450 days and a SD of 20 days.
1. Should we use a one-tailed test or a two-tailed test?
2.What is the standard deviation of the comparison distribution (standard error) for our vitamin study?
3.If we set our alpha at .05, what is our cutoff for the vitamin study?
4.What can we conclude from our vitamin study?
a.We found support for the idea that vitamins have an effect on the lifespan of rats, and it looks like a negative one.
b.We failed to reject our null hypothesis so vitamins have no effect on health.
c.We proved that vitamins improve health.
d.We proved that vitamins reduce health.
a.We found support for the idea that vitamins have an effect on the lifespan of rats, and it looks like a negative one.
b.We failed to reject our null hypothesis so vitamins have no effect on health.
c.We proved that vitamins improve health.
d.We proved that vitamins reduce health.
Explanation / Answer
sol1:
decide to study the effects of daily vitamin use
its a two-tailed test
Sol2:
std error=std dev/sqrt(samplesize)
=20/sqrt(25)
=20/5
=4
solution3:
.If we set our alpha at .05, what is our cutoff for the vitamin study
Solution4:
t=1450-0/20/sqrt(25)
=1450/20/5
=1450/4
=362.5
df=n-1=25-1=24
alpha=0.05
0.05/2=0.025
p value=<0.00001
Reject Null nypotheisis
result is significant at p<0.05
b.We failed to reject our null hypothesis so vitamins have no effect on health.
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