Answer:
2 - 3i
is 2 - the square root of -9
2 -√-9
2 + √9
2 + 3 = 5
<em><u>Thank you (I dont know if these answers are 100% correct but I tried my best!)</u></em>
Answer:
The answer is below
Step-by-step explanation:
From the table, the mean (μ) = 1390.75 and the standard deviation (σ) = 518.75
The confidence level (C) = 90% = 0.9
α = 1 - C = 1 - 0.9 = 0.1
α/2 = 0.1 / 2 = 0.05
The z score of α/2 (0.05) is the same as the z score of 0.45 (0.5 - 0.05) which is equal to 1.645.
The margin of error (E) is given as:

The confidence interval = μ ± E = 1390.75 ± 228.07 = (1162.68, 1618.82)
The confidence interval is between 1162.68 and 1618.82.
<h2>
Answer:37 paintings of $50 and 15 paintings of $75</h2>
Step-by-step explanation:
Let
be the number of paintings Ella sells for $
.
Let
be the number of paintings Ella sells for $
.
Profit made through $
paintings is 
Profit made through $
paintings is 
So,total profit is given by 
It is given that total profit is $
So,
..(i)
Given that the total number of prints is 
So,
..(ii)
using (i) and (ii),


Answer:


And we can find the limits in order to consider values as significantly low and high like this:


Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
Solution to the problem
For this case we can consider a value to be significantly low if we have that the z score is lower or equal to - 2 and we can consider a value to be significantly high if its z score is higher tor equal to 2.
For this case we have the mean and the deviation given:


And we can find the limits in order to consider values as significantly low and high like this:


Answer:
2.87%
Step-by-step explanation:
We have the following information:
mean (m) = 200
standard deviation (sd) = 50
sample size = n = 40
the probability that their mean is above 21.5 is determined as follows:
P (x> 21.5) = P [(x - m) / (sd / n ^ (1/2))> (21.5 - 200) / (50/40 ^ (1/2))]
P (x> 21.5) = P (z> -22.57)
this value is very strange, therefore I suggest that it is not 21.5 but 215, therefore it would be:
P (x> 215) = P [(x - m) / (sd / n ^ (1/2))> (215 - 200) / (50/40 ^ (1/2))]
P (x> 215) = P (z> 1.897)
P (x> 215) = 1 - P (z <1.897)
We look for this value in the attached table of z and we have to:
P (x> 215) = 1 - 0.9713 (attached table)
P (x> 215) =.0287
Therefore the probability is approximately 2.87%