A new kind of typhoid shot is being developed by a medical research team. The old typhoid shot was known to protect the population for a mean time of 36 months, with a standard deviation of 3 months. To test the time variability of the new shot, a random sample of 23 people were given the new shot. Regular blood tests showed that the sample standard deviation of protection times was 1.7 months. Using a 0.05 level of significance, test the claim that the new typhoid shot has a smaller variance of protection times. (f) Find a 90% confidence interval for the population standard deviation. (Round your answers to two decimal places.) lower limit upper limit How do i get the lower and upper numbers?
n = Sample Size = 23
s = Sample Standard Deviation =1.7
= 0.10
Confidence Interval is given by:
Degrees of freedom = n - 1 16 - 1 = 15
Low side
From Table:
Low Side:
High side:
From Table:
High side:
So,
Confidence Interval:
1.32 < <
2.44
So,
Lower number = 1.32
Upper number = 2.44
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