Decay Problem 3
Algebra
Level
3
A substance decays at a constant compounding rate. It is 5kg in year 2001 and 100g in 2003. What was its amount in 1997?
12500 kg
500 kg
14.8 kg
25000 kg
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1 solution
5kg = 5000g
5000/100 = 50, this means that it decreased by 50x in 2 years (2003-2001 = 2)
1997 is 4 years before 2001, so:
5x50x50 = 12500kg
To work out the decay rate:
Also, we have 12500 = x^4 * 5
So x, the rate of decay, is = to 25^(0.25) = 2.236067977