Answer:
400
Step-by-step explanation:
To find the scale factor, you need to find out how much the initial value was multiplied by to get the new value. To do that, you need to divide the new value by the initial value. Make sure the units are the same; don't divide 1000 feet by 30 inches!
Hope this helps!
Let be the population mean .
By observing the given information, we have :-
Since the alternative hypotheses is two tailed so the test is a two-tailed test.
We assume that the life of a large shipment of CFLs is normally distributed.
(a) Given : Sample size : n=81 , since n>30 so we use z-test.
Sample mean :
Standard deviation :
Test statistic for population mean :-
The critical value (two-tailed) corresponds to the given significance level :-
Since the observed value of z (-1.4) is less than the critical value (1.96) , so we do not reject the null hypothesis.
Hence, we conclude that we have enough evidence to accept that the mean life is different from 7450 hours .
(b) The p-value : , it means that the probability that the life of CFLs less than 7240 and greater than 7240 is 0.1615.
(c) The confidence interval for population mean is given by :-
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