1.Using the following data, calculate the: a. payback period b. internal rate of return c. net present value. Project cost: $100000 Estimated life: 5 Years Estimated residual value: $15,000 Annual net cash flow: $30,000 Required rate of return: 10%

I'm not sure the formula i apply is that right b,)internal rate of return answer

100,000= 30000/ (1+ r)+ 30000/(1+r)²+30000/(1+r)³+30000/(1+r)⁴+30000/(1+r)⁵

^{100,000=165000/(1+r)}

^(1+r)=1.65

R=0.2845

My answer is wrong. i just want to know how to calculate like step by step because I can't use Excel

Thanks

can you let me know my formula is that right?and the step of this calculation