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Hints and solutions to
Problem of the day for Friday, February 21
A crowd watching a parade fills the sidewalks on both sides of the
street for
a distance of 2 miles. The sidewalks are 10 feet deep and an average
person
needs 4 square feet to stand on. Which of the following is the best
estimate for the number of people in the crowd:
- (a) 25,000 people
- (b) 50,000 people
- (c)
100,000 people
- (d) 250,00 people
- (e) 500,000 people
(The picture above is of the Democratic Party parade in 1880.)
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We'll assume the people use the space as efficiently as possible. So
we need to
figure out how many square feet of sidewalk there are.
-
Since the street is 2 miles long, the sidewalk on each side is
roughly a
rectangle with width 10 feet and length 2 miles (or 10,560 feet).
-
So the total area on both sides of the street is 2 x 10 x 10,560, or
211,200
square feet. (Given that we're estimating pretty roughly here, it's
enough to say
a little over 200,000 square feet).
-
Since each person needs 4 square feet to stand, we divide 200,000 by
4 to
get around 50,000 people, so the answer is (b).
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