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.
Answer:
36h+81m
Step-by-step explanation:
9*4h+9*9m=36h+81m
Answer:
84
Step-by-step explanation:
let a be the 1's digit and b the 10's digit, then
a = 2b ← twice the 10's digit, thus
sum = 2b + b = 12, that is
3b = 12 ( divide both sides by 3 )
b = 4
and a = 2b = 2 × 4 = 8
The 2 digit number is 84
Solve the following system using elimination:
{3 x - 4 y = -24 | (equation 1)
{x + y = -1 | (equation 2)
Subtract 1/3 × (equation 1) from equation 2:
{3 x - 4 y = -24 | (equation 1)
{0 x+(7 y)/3 = 7 | (equation 2)
Multiply equation 2 by 3/7:
{3 x - 4 y = -24 | (equation 1)
{0 x+y = 3 | (equation 2)
Add 4 × (equation 2) to equation 1:
{3 x+0 y = -12 | (equation 1)
{0 x+y = 3 | (equation 2)
Divide equation 1 by 3:
{x+0 y = -4 | (equation 1)
{0 x+y = 3 | (equation 2)
Collect results:
Answer: {x = -4, y = 3