Answer:
The sample size is 
Step-by-step explanation:
From the question we are told that
The margin of error is E =4.266
The standard deviation is 
From the question we are told the confidence level is 99% , hence the level of significance is
=> 
Generally from the normal distribution table the critical value of 
is
Generally the sample size is mathematically represented as
![n = [\frac{Z_{\frac{\alpha }{2} } * \sigma }{E} ] ^2](https://tex.z-dn.net/?f=n%20%3D%20%5B%5Cfrac%7BZ_%7B%5Cfrac%7B%5Calpha%20%7D%7B2%7D%20%7D%20%2A%20%20%5Csigma%20%7D%7BE%7D%20%5D%20%5E2)
=> ![n = [\frac{2.58 * 2.539 }{4.266} ] ^2](https://tex.z-dn.net/?f=n%20%3D%20%5B%5Cfrac%7B2.58%20%20%2A%20%202.539%20%20%7D%7B4.266%7D%20%5D%20%5E2)
=>
Answer:
C. 0.98
Step-by-step explanation:
Let x be the mean of Company A and B annual profit and x/2 and y are standard deviation of Company A and B annual profit.
P(B<0) = 0.9*P(A<0)
P(Z<(0-x)/y) = 0.9*P(Z<(0-x)/(x/2))
P(Z<-x/y) = 0.9*P(Z<-2)
P(Z<-x/y) = 0.0205
x/y =2.04
Or y/x = 1 /2.05
y/x =0.49
Ratio of the standard deviation of company B annual profit to the standard deviation of company A annual profit =y/(x/2)
= 2*(y/x)
= 2*0.49
= 0.98
Answer:
Counselor's estimate isn't correct.
Step-by-step explanation:
Total number of students in university = 30,600
2% break 3 of the languages
Therefore, 2/100 × 30600 = 612 students break 3 of the languages in the University according to the counselor.
In a random sample of 240 students, 20 break 3 of the languages.
% = 20/240 × 100 = 8.33%
SinceTotal number of students = 30,600
Therefore, 30,600/240 = 127.5
Which means 127.5 × 20 = 2550.
Which means 2550 students break 3 of the languages as against the 612 students stated by the counselor.
The answer I’m guessing would be B :)
