Question 1170595

Xian opened a savings account and put Php 6,250 in it. Each year, the account increases by 20%. How many years will it take the account to reach Php 12,960?
<pre>Let the time it takes for the account to have PhP 12,960, be t
Then we get: {{{matrix(3,3, "12,960", "=", "6,250"(1 + .2)^t,
"12,960"/"6,250", "=", 1.2^t,
"1,296"/625, "=", 1.2^t)}}}
Converting to LOGARITHMIC form, the time it takes for the account to have PhP 12,960, or {{{highlight_green(matrix(1,5, t, "=", log (1.2, ("1,296"/625)), "=", highlight(matrix(1,2, 4, years))))}}}