Special Populations Flashcards
7 cards from real AMC 12 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Special Populations flashcards as text
A bacteria population of 500 doubles every 3 hours. What is the population after 12 hours?
Answer: 8000
12 hours is 4 doubling periods, so 500·2^4 = 8000.
A population of 1000 grows by 10% per year, compounded annually. What is it after 2 years?
Answer: 1210
1000·1.1^2 = 1210.
A population halves every 5 years. How many years does it take to drop from 6400 to 400?
Answer: 20
6400/400 = 16 = 2^4, so it takes 4 half-lives, or 20 years.
A population grows exponentially and triples in 4 years. How long does it take to become nine times its original size?
Answer: 8 years
Nine times is two triplings, so 2·4 = 8 years.
A population increases by 20% one year and then decreases by 20% the next year. What is the net percent change?
Answer: -4%
1.2·0.8 = 0.96, a 4% decrease.
Town A has 300 people with mean age 40, and Town B has 200 people with mean age 30. What is the mean age of the combined population?
Answer: 36
(300·40 + 200·30)/500 = 18000/500 = 36.
In a population, 60% are women. If 30% of women and 20% of men wear glasses, what percent of the population wears glasses?
Answer: 26%
0.6·0.3 + 0.4·0.2 = 0.18 + 0.08 = 0.26.
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