Hi Heba S.
11.581 years
Doubling says that A = 2P or 2000
Using the formula
A=P(1+r/n)nt
A=2000
P=1000
r = 6% write as a decimal
n=12
You will need to use logarithms to find t
2000=1000(1+.06/12)12t
2000 = 1000(1+0.005)12t
2000 = 1000(1.005)12t
2000/1000 = (1.005)12t
2 = (1.005)12t
log10(2)/log10(1.005) = 12t
Can you solve for t?
Brenda D.
tutor
Thank you Peter R. It also serves as a quick useful ball park figure before you get the logs. If the problem had read to the nearest whole number, 12 would certainly fit. I do wonder if the student's class covers Rule of 72 since they required use of the formula given. The very existence of more than one route toward solving a problem, makes math the great subject that it is.
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03/25/22
Frank T.
tutor
Rule of 72 is an estimate - it can let the student know the answer is correct. If the answer came to 36, for example, the Rule of 72 suggests that answer is incorrect.
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03/25/22
Peter R.
03/25/22