Answer:
A sample of 17 must be selected.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Z-table as such z has a p-value of 
.
That is z with a pvalue of 
, so Z = 2.054.
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
The standard deviation from a previous study is 4 hours.
This means that 
How large a sample must be selected if he wants to be 96% confident of finding whether the true mean differs from the sample mean by 2 hours?
A sample of n is required.
n is found for M = 2. So
Simplifying both sides by 2:
Rounding up:
A sample of 17 must be selected.
9514 1404 393
Answer:
(x -7)(7x +4)
Step-by-step explanation:
The term -45x can be rewritten using factors of (7)(-28) that have a total of -45. Those factors would be ...
(7)(-28) = (4)(-49)
7x^2 +4x -49x -28 = x(7x +4) -7(7x +4) = (x -7)(7x +4)
8b+12-b=8+7b+4
7b+12=12+7b
-7b
7b-7b+12=12
-12 -12
0= 12-12
0=0
Answer:
(12/1.35)^2 ~= 79.012346
(roughly equal to ~=)
Step-by-step explanation:
divide both sides by 1.35
12/1.35 = √x
square both sides to get rid of √
(12/1.35)^2 ~= 79.012346
