Answer:
10/3 hours
Step-by-step explanation:
12x=15x-10
12x-15x=15x-10-15x
-3x=-10
-3x/-3=-10/-3
x=10/3
Add the 2 values togetehr
336473894875785686598685965867 - 67843993 = 3*10^29
Answer:
The minimum sample size that should be taken is 62.
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 the margin of error M as such

In which
is the standard deviation of the population and n is the size of the sample.
If we want to be 90% confident that the sample mean is within 1 word per minute of the true population mean, what is the minimum sample size that should be taken
This is n when
. So





The minimum sample size that should be taken is 62.