Answer:
4a-8
Step-by-step explanation:
(-4×a)+(-4×2)
Distributive property
2.3 rounds to 2
because if the decimal is 5 or above you round up, if its less than 5 it stays the same. for example 2.6 round to 3 but 2.4 becomes 2
Answer:
57.3125%
Step-by-step explanation:
Add up all of the values to get 458.5. Then divide by how many values you were given which is 8. So you take 458.5 and divide it by 8 to get the answer.
Answer:
We need a sample size of at least 369.
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:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
How large of a sample size is required?
We need a sample size of at least n.
n is found when
. So






Rounding up
We need a sample size of at least 369.
We can build a system of two linear equations with two unknowns with the info provided in the problem, one with Kelsey info and one with Mitch info like so:
Lets call p the amount on peak minutes and n the amount of non-peak minutes:
45p + 50n = 27.75
70p + 30n = 36
lets reduce the equations dividing the first by 5:
9p + 10n = 5.55
<span>70p + 30n = 36
</span>now, to eliminate n, lets multiply the first equation by -3 and add the two equations:
-27p - 30n = -16.65
<span>70p + 30n = 36
</span>----------------------------
43p + 0 = 19.35
p = 19.35<span>/43
p = 0.45
therefore the peak rate is $0.45 per minute
lets substitute in one of the original equations this result:
</span><span>45p + 50n = 27.75
</span>45(0.45) + 50n = 27.75
20.25 <span>+ 50n = 27.75
50n = 27.75 - 20.25
50n = 7.5
n = 7.5/50
n = 0.15
therefore the non-peak rate per minute is $0.15</span>