Answer:
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence level of 
, we have the following confidence interval of proportions.
In which
is the estimate
z is the zscore that has a pvalue of 
, also called the critical value.
The standard error is:
90% confidence level critical value
So 
, z is the value of Z that has a pvalue of 
, so 
.
Estimate:
72 petty theft cases and finds 45 of these have gone unsolved.
So 
Standard error:
Answer:
162/9 = 18 water bottles per case
Answer:
10 spiders and 12 ants
Step-by-step explanation:
You need to create two equations
s = # of spiders
a = # of ants
s + a = 22 heads
since each spider and ant has one head
8s + 6a = 152 legs
since every spider has 8 legs and every ant has 6
s + a = 22 can be turned into s = 22 - a
now use substitution
8(22 - a) + 6a = 152
176 - 8a + 6a = 152
176 - 2a = 152
24 = 2a
a = 12
now that you have the number of ants you can solve for the number of spiders
s + a = 22
s + 12 = 22
s = 10
