Answer:
1)x=15
2)x=38
3)x=7
4)x=10
Step-by-step explanation:
<em>Hi!</em>
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<em>These can be set up as systems of equations.</em>
<em> </em>
<em>Let b = the number of birds, and let d = the number of dogs.</em>
<em> </em>
<em>b + d = 21</em>
<em> </em>
<em>2b + 4d = 76 (this is because birds have 2 legs and dogs have 4 legs.)</em>
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<em>You can solve this using either elimination or substitution.</em>
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Answer: I think its A and C
Step-by-step explanation:
Please mark me brainliest
Answer:
The need to sample 76 days.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
So it is z with a pvalue of 
, so 
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
How many days do they need to sample
We need to sample n days.
n is found when M = 300.
We have that 
So
Rounding up
The need to sample 76 days.
