In: Statistics and Probability
2. The measured residual flame time, in seconds, for strips of treated children’s nightwear are given in the following table.
9.85 |
9.93 |
9.75 |
9.77 |
9.67 |
9.87 |
9.67 |
9.94 |
9.85 |
9.75 |
9.83 |
9.92 |
9.74 |
9.99 |
9.88 |
9.95 |
9.95 |
9.92 |
9.93 |
9.89 |
Suppose a true average flame time of at most 9.75 seconds had been mandated. Does the data suggest that this condition has not been met? Carry out an appropriate test after first investigating the plausibility of assumptions that underlie your method of inference. Use the recommended sequence of steps and reach a conclusion using a significance level of 0.01:
7. Compare the selected or specified significance level to the P-value to decide whether H0 should be rejected, and state this conclusion in the problem context:
2.
1.
the parameter of interest and describe it in the context of the
problem situation:
T test for single mean with unknown population standard
deviation
Given that,
population mean(u)=9.75
sample mean, x =9.8525
standard deviation, s =0.0965
number (n)=20
null, Ho: μ=9.75
alternate, H1: μ!=9.75
level of significance, α = 0.01
from standard normal table, two tailed t α/2 =2.861
since our test is two-tailed
reject Ho, if to < -2.861 OR if to > 2.861
we use test statistic (t) = x-u/(s.d/sqrt(n))
to =9.8525-9.75/(0.0965/sqrt(20))
to =4.75
| to | =4.75
critical value
the value of |t α| with n-1 = 19 d.f is 2.861
we got |to| =4.75 & | t α | =2.861
make decision
hence value of | to | > | t α| and here we reject Ho
p-value :two tailed ( double the one tail ) - Ha : ( p != 4.7502 )
= 0.0001
hence value of p0.01 > 0.0001,here we reject Ho
ANSWERS
---------------
2.
null, Ho: μ=9.75
3.
alternate, H1: μ!=9.75
4.
we use test statistic (t) = x-u/(s.d/sqrt(n))
5.
test statistic: 4.75
critical value: -2.861 , 2.861
decision: reject Ho
6.
p-value: 0.0001
7.
p value is less than alpha value
we have enough evidence to support the claim that true average
flame time of at most 9.75 seconds had been mandated