Answer:
Step-by-step explanation:
If the males make up 60% of the class then
The females make up 100 - 60 = 40% of the class.
Females = 40% * x where x = the class size.
380 = 40/100 * x
380*100 =38000
38000 = 40 x
38000/40 = x
x =950
Answer: 
Step-by-step explanation:
Given : Sample size : 
Sample mean : 
Standard deviation : 
Significance level : 
Critical value : 
Formula to find the confidence interval for population mean :-

Hence, a 90% confidence interval estimate of the population mean of all students = 
Answer:
3d + 1
I'm pretty sure it's the same thing.