Answer:
a) It can be used because np and n(1-p) are both greater than 5.
Step-by-step explanation:
Binomial distribution and approximation to the normal:
The binomial distribution has two parameters:
n, which is the number of trials.
p, which is the probability of a success on a single trial.
If np and n(1-p) are both greater than 5, the normal approximation to the binomial can appropriately be used.
In this question:
So, lets verify the conditions:
np = 201*0.45 = 90.45 > 5
n(1-p) = 201*(1-0.45) = 201*0.55 = 110.55 > 5
Since both np and n(1-p) are greater than 5, the approximation can be used.
3n + 7 ><span> 4n
-3n -3n
7 > n
n</span> < 7
Answer:
At least 547 records need to be studied.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence interval 
, we have the following confidence interval of proportions.
In which
Z is the zscore that has a pvalue of 
.
And the margin of error is:
95% confidence interval
So 
, z is the value of Z that has a pvalue of 
, so 
.
In this problem, we have that:
At least 547 records need to be studied.
Step-by-step explanation:
if you want I will prove
-4x + 7y = -8 . . . (1)
-5x + 6y = 1 . . . .(2)
(1) x 5 => -20x + 35y = -40 . . . (3)
(2) x 4 => -20x + 24y = 4 . . . . .(4)
(3) - (4) => 11y = -44 => y = -44/11 = -4
From (2), -5x + 6(-4) = 1 => -5x - 24 = 1 => -5x = 1 + 24 = 25 => x = 25/-5 = -5
Therefore, x = -5, y = -4
