Saturday, 28 December 2013

`(1+0.09/12)^(12t) = 3` Solve the equation accurate to three decimal places

`(1+0.09/12)^(12t) = 3`


In solving these kind of problems we need to use the logarithm.


Take the log of both sides of the equation.


`log_(10)((1+0.09/12)^(12t)) = log_10(3)`


With logarithms we know that;


`log(a^b) = bloga`


using that rule;


`log_(10)((1+0.09/12)^(12t)) = 12tlog_10(1+0.09/12)`



`12tlog_10(1+0.09/12) = log_10(3)`



`log_10(1+0.09/12) = log_10(1.0075) = 0.003245`


`log_10 (3) = 0.4771`



`12txx0.003245 = 0.4771`


`t = 0.4771/(12xx0.00325) = 12.252`



So the answer is t = 12.252


`(1+0.09/12)^(12t) = 3`


In solving these kind of problems we need to use the logarithm.


Take the log of both sides of the equation.


`log_(10)((1+0.09/12)^(12t)) = log_10(3)`


With logarithms we know that;


`log(a^b) = bloga`


using that rule;


`log_(10)((1+0.09/12)^(12t)) = 12tlog_10(1+0.09/12)`



`12tlog_10(1+0.09/12) = log_10(3)`



`log_10(1+0.09/12) = log_10(1.0075) = 0.003245`


`log_10 (3) = 0.4771`



`12txx0.003245 = 0.4771`


`t = 0.4771/(12xx0.00325) = 12.252`



So the answer is t = 12.252


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