Answer:
The 95% of confidence intervals
(2.84 ,2.99)
Step-by-step explanation:
A random sample of 20 accounting students results in a mean of 2.92 and a standard deviation of 0.16
given small sample size n =20
sample mean x⁻ =2.92
sample standard deviation 'S' =0.16
level of significance ∝ = 0.95
The 95% of confidence intervals
the degrees of freedom γ=n-1 =20-1=19
t-table 2.093
(2.92-0.0748,2.92+0.0748)
(2.84 ,2.99)
Therefore the 95% of confidence intervals
(2.84 ,2.99)
Answer:
68% of these phones last 3.87 years.
Step-by-step explanation:
Exponential distribution:
The exponential probability distribution, with mean m, is described by the following equation:
In which is the decay parameter.
The probability that x is lower or equal to a is given by:
Which has the following solution:
The probability of finding a value higher than x is:
The average lifetime of a certain new cell phone is 3.4 years.
This means that
So
68% of these phones last how long (in years)?
This is x for which:
Then
68% of these phones last 3.87 years.