The number of fish in a like grows steadily at a rate of10%per year. If there are 242000 fish in the lake now, find the number of fish.
a)after 3 years,
b)2 years ago.
The population of a city is originally 4800 000. If the population decreses steadily at a rate of 5% each year, what will be the population after 3 years?
The weight of a radioactive chemical decreases by50% every1600 years.If its original weight is 4kg, what will its weight be after 19 200 years?
The depreciation rate of a bicycle is 12% per year. If its present value is $1936, find its value
a) in 3 years's time
b) 2 years ago.
F.3 compound interest 數
2009-11-12 5:41 pm
回答 (2)
2009-11-12 6:15 pm
✔ 最佳答案
(1a) 242000 x 1.13 = 322102(b) 242000/1.12 = 200000
(2) 4800000 x 0.953 = 4115400
(3) 19200 years = 1600 years x 12
Thus the weight will be 4 x 0.512 = 0.000977 kg = 0.977 g
(4a) 1936 x 0.883 = 1319.3
(b) 1936/0.882 = 2500
參考: Myself
2009-11-12 8:29 pm
1b) let the no. of the fish be X 2 years ago
X (1+10%)^2 = 242000
4b) let 2 years ago its value be $X
X(1 - 12%) = 1936
X (1+10%)^2 = 242000
4b) let 2 years ago its value be $X
X(1 - 12%) = 1936
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