a project has an initial cost of $6,640. the expected cash inflows are $550, $1,700, $2,100, and $3,900 over the next 4 years, respectively. what is the payback period?

a. 3.09 yrs

b. 2.70 yrs

c.3.59yrs

d. 3.24yrs

e. 2.66 yrs