Question

A)if a sum invested dains 10% each yr, how long it will take to duoble its value?
B)if an object depreciates in value by 10% each yr, how long will it take until only half of the original value remains?
C)why aren't these two answers (A & B) the same?
D)is there a rate, used for both gain Aand depreciation, for which those two answers would actually be the same..

but i worked out Q A) i got 7.273 yrs
and Q B) i got 6.579.., b ut im not sure is these answers correct..

Answer 1

A) Your answer is correct
(1.1)^7.273 = 2.000
B) Your answer is correct
(0.9)^6.579 = 0.500
C) The first situation is equivalent to
(1/1.1)^7.283 = (0.9091)^7.273 = 0.500 , not
(0.9)^6.579 = 0.500
(D) No. The math is different. A 50% loss requires losing 10% of the original amount 5 times. Doubling requires earning 10% of the original amount 10 times. Compounding helps make the time requirements more nearly equal, but they still remain different

Answer 2

tanx drwls.. :D