You Intend to Accumulate $100,000 in 10 Years Instead of 20

You intend to accumulate $100,000 in 10 years instead of 20 years by making equal monthly investment contributions. Will the monthly contribution for a 10-year plan be: (i) Twice the monthly contribution for a 20-year plan? (ii) Less than twice the monthly contributions? or (iii) More than twice the monthly contributions? Assume the same rate of return in both cases. Give the reasoning for your choice.