Answer: it’s the 3’rd one
Explanation: I hope this helps
1/2 t-4(2+t)=20
1/2 t-8-4t=20
least common multiple=2
t-16-8t=40
-7t=40+16
-7t=56
t=56/-7=-8
Answer: t=-8
To check
-8/2 - 4(2-8)=-4-4(-6)=-4+24=20
Answer:
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Step-by-step explanation:
Answer:
The 80% confidence interval for the mean number of words a third grader can read per minute is between 40.4 wpm and 40.8 wpm.
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 Ztable as such z has a pvalue of
.
So it is z with a pvalue of
, so 
Now, find M as such

In which
is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 40.6 - 0.2 = 40.4 words per minute.
The upper end of the interval is the sample mean added to M. So it is 40.6 + 0.2 = 40.8 words per minute.
The 80% confidence interval for the mean number of words a third grader can read per minute is between 40.4 wpm and 40.8 wpm.