The number of cases of a new disease can be modeled by the quadratic regression equation y = –2x2 + 36x + 6, where x represents
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Answer:
Step-by-step explanation:
In the past, mean of age of employees
i.e.
Recently sample was taken
n = sample size = 60
Mean of sample = 45
Std dev of sample s = 16
(Right tailed test)
Since only population std deviation is known we can use t test only
Std error =
Mean difference = 45-40 =5
Test statistic t=
df = 60
p value =0.008739
Since p < 0.05 we reject null hypothesis
The mean age has increased.