Answer:
20 fence posts.
Step-by-step explanation:
Calvin is building a fence. The fence will enclose a 100 square foot area, 10 ft wide by 10 ft long. Calvin can put fence posts 2 feet apart.
Now, if he puts a fence post at each corner of the building, then considering each length of the building there will be 
posts along each length.
Now, considering each width of the building there will be 
posts (excluding the corner posts) along each width.
Therefore, in total there will be (6 + 6 + 4 + 4) = 20 fence post in the total fence. (Answer)
Answer:
99.5 minutes
Step-by-step explanation:
50=45
495=?
495×45÷50=99.5
Let X be the number of lightning strikes in a year at the top of particular mountain.
X follows Poisson distribution with mean μ = 3.8
We have to find here the probability that in randomly selected year the number of lightning strikes is 0
The Poisson probability is given by,
P(X=k) = 
Here we have X=0, mean =3.8
Hence probability that X=0 is given by
P(X=0) = 
P(X=0) = 
P(X=0) = 0.0224
The probability that in a randomly selected year, the number of lightning strikes is 0 is 0.0224
