Answer:
The equation is
at a rate of -23%.
Step-by-step explanation:
Decay can be represented by the equation
. We can find the rate at which it decays by using t=3 hours and A=3000. This means
in this context.
After substituting, we divided by 6000 to each side to get 0.5 on the left. Now to solve for r, we will take the natural log of both sides and use log rules to isolate r.
We know
so we were able to cancel it out and divide both sides by 3.
We solve with a calculator
We change -0.23 into a percent by multiplying by 100 to get -23% as the rate.
The equation is
Answer:
The minimum sample size needed is 125.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.

In which
z is the zscore that has a pvalue of
.
The margin of error is:

For this problem, we have that:

99% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
What minimum sample size would be necessary in order ensure a margin of error of 10 percentage points (or less) if they use the prior estimate that 25 percent of the pick-axes are in need of repair?
This minimum sample size is n.
n is found when 
So






Rounding up
The minimum sample size needed is 125.
Answer:
It is D
Step-by-step explanation:
6 x 11 = 66
3 x 9 = 27