Answer:
37.5 Gallons will be used after a 15-minute shower.
50 Gallons will be used after a 20-minute shower.
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Answer:
27 chickens
Step-by-step explanation:
A chicken farmer also has cows for a total of 30 animals
Both animals have a total of 66 legs
Let a represent the number of chicken
Let b represent the number of cows
a + b= 30........equation 1
Since a chicken has only two legs and a cow has four leg then, the expression can be represented as
2a + 4b= 66........equation 2
From equation 1
a + b= 30
a = 30-b
Substitute 30-b for a in equation 2
2a + 4b= 66
2(30-b) + 4b= 66
60 - 2b + 4b= 66
60 + 2b= 66
2b= 66-60
2b= 6
b= 6/2
b= 3
Substitute 3 for b in equation 1
a + b = 30
a + 3=30
a= 30-3
a= 27
Hence the farmer has 27 chickens
We need to find out how many adults must the brand manager survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage.
From the given data we know that our confidence level is 90%. From Standard Normal Table we know that the critical level at 90% confidence level is 1.645. In other words, 
.
We also know that E=5% or E=0.05
Also, since, 
is not given, we will assume that =0.5. This is because, the formula that we use will have 
in the expression and that will be maximum only when =0.5. (For any other value of , we will get a value less than 0.25. For example if, is 0.4, then 
and thus, 
.).
We will now use the formula
We will now substitute all the data that we have and we will get
which can approximated to n=271.
So, the brand manager needs a sample size of 271
