At which rate per annum of simple interest, the sum will triples itself in $16$ years$?$

Find the simple interest, when:

Principal $=₹ 2000$, Rate of interest  $=5\%$ per annum and Time $=5$ years.

If the simple interest when Principal $=₹ 500$, Rate of interest $= 12.5\%$ per annum and Time$=4$ years is $₹k$, then find the value of $k$

Find the simple interest, when:

Principal$=₹ 4500$, Rate of interest$=4\%$% per annum and Time$=6$ months.

If the simple interest$=₹\mathrm{k}$, when:

Principal$=₹12000$, Rate of interest$=18\%$ per annum and Time$=4$ months. Find the value of $\mathrm{k}$.