If R35 000 accumulates to R48 320 at a continuous compounded rate of 8,6%, then the term under consideration is:

[1] 2,77 years.

[2] 3,75 years.

[3] 3,91 years.

[4] 4,43 years.

[5] 6,23 years.

Please give formula used to calculate answer as i cant not seem to derive the correct one.