what is the r.o.i??????????
There's no "quick formula" way to calculate the monthly rate of interest, as you get 17 months of interest on the first 1000, 16 on the second, 15 on the third, and so on, down to 1 for the 17th, so you get:
1000 (x17 + x16 + x15 + ... + x) = 17,600
x17 + x16 + x15 + ... + x - 17.6 = 0
where x is the monthly multiplier (e.g. for 1% monthly interest, x = 1.01).
There's no formula for solving a polynomial of degree 5 or higher; you have to use an approximation method like Newton-Raphson or Halley, both of which require at least some knowledge of calculus.
Copy and paste:
x^17 + x^16 + x^15 +x^14 + x^13 + x^12 +x^11 + x^10 + x^9 +x^8 + x^7 + x^6 + x^5 +x^4 + x^3 + x^2 + x - 17.6 = 0
Awesome. Excel continues to surprise me. I had to give it an initial guess ... =IRR(C3:C20,0.4%) = 0.38417091%Quote: MathExtremist
ROI is just return divided by investment, so 600/17000 = 3.53%. If you want the IRR (internal rate of return) you can compute in a spreadsheet using the IRR function. Type in -1000 in 17 rows (negative representing outgoing cashflow, aka investment) and in the 18th row type 17600 (positive representing incoming cashflow, aka liquidation). Then compute the IRR over those 18 rows and you'll get the periodic rate of return which is 0.384%.