I'm not sure what you meant after alligators, if it was or or for, but I think it was for so I'm going with that. If 60 increase every 5 years, it would be 60 over 5 (in fractions). So I would do 60 divided by 5, which would be 12. So that means 12 increase every year. I'm not sure what mean meant either, if you're talking about the mathematical mean, but you can't solve the mean in this problem. The Answer: The yearly change in the alligator population would be 12.
1. 23,763 + 20 = 23,783
2. 23,763 + 200 = 23,963
3. 75,379 - 5 = 75,374
4. 476,932 - 1,000 = 475,932
Greater than = Add
Less than = Subtract
Comment if you need any help.
Answer:
100 students should be surveyed in order to cut the width of the interval down from 3 hours to 1.5 hours
Step-by-step explanation:
Given that a 95% confidence interval, based upon a sample of size 25, for the mean number of hours of sleep that college students get per night was 5 to 8 hours.
Confidence interval = (5,8)
This implies that mean = 6.5 and margin of error = 1.5
i.e. 
If the interval width to be cut into half then the
New confidence interval = (5.75, 7.25)
Margin of error = 0.75

This is possible only when new n= 100
Hence sample size should be increased to 100
100 students should be surveyed in order to cut the width of the interval down from 3 hours to 1.5 hours