Answer:
The margin of error for a 90% confidence interval is 16.4
Step-by-step explanation:
We are given the following in the question:
Sample size, n = 25
Standard deviation = 50

Margin of error =

Putting the values, we get,

Thus, the margin of error for a 90% confidence interval is 16.4
Answer:
0.5981 = 59.81% probability that three or less of the selected adults have saved nothing for retirement
Step-by-step explanation:
For each adult, there are only two possible outcomes. Either they save nothing for retirement, or they save something. The probability of an adult saving nothing for retirement is independent of any other adult. This means that the binomial probability distribution is used to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
20% of adults in the United States save nothing for retirement (CNBC website).
This means that 
Suppose that sixteen adults in the United States are selected randomly.
This means that 
What is the probability that three or less of the selected adults have saved nothing for retirement?
This is:

In which






0.5981 = 59.81% probability that three or less of the selected adults have saved nothing for retirement
Answer:126
Step-by-step explanation: your welcome
Answer:
Step-by-step explanation:
Given that 33.4% of people have sleepwalked.
Sample size n =1459
Sample favourable persons = 526
Sample proportion p = 
Sample proportion p is normal for large samples with mean = 0.334 and
std error = 
a) P(526 or more of the 1459 adults have sleepwalked.)

b) Yes, because hardly 1.4% is the probability
c) 33.4 is very less compared to the average. Either sample should be improved representing the population or population mean should be increased accordingly.