A study of the effects of exercise used rats bred to have high or low capacity f
ID: 3316401 • Letter: A
Question
A study of the effects of exercise used rats bred to have high or low capacity for exercise. There were 8 high-capacity and 8 low-capacity rats. The 8 high-capacity rats had mean blood pressure 89 with standard deviation 9, and the 8 low-capacity rats had mean blood pressure 105 with standard deviation 13. Using table C of your textbook (without additional software) what is the margin of error for a 95% confidence interval for the difference of the two means (low capacity - high capacity)? (Answer to the nearest hundredth.)
Explanation / Answer
given that,
mean(x)=105
standard deviation , s.d1=13
number(n1)=8
y(mean)=89
standard deviation, s.d2 =9
number(n2)=8
I.
stanadard error = sqrt(s.d1^2/n1)+(s.d2^2/n2)
where,
sd1, sd2 = standard deviation of both
n1, n2 = sample size
stanadard error = sqrt((169/8)+(81/8))
= 5.59
II.
margin of error = t a/2 * (stanadard error)
where,
t a/2 = t -table value
level of significance, = 0.05
from standard normal table, two tailed and
value of |t | with min (n1-1, n2-1) i.e 7 d.f is 2.365
margin of error = 2.365 * 5.59
= 13.221
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