Answer:
A) future value = present value (1 + rate)ⁿ
420,000 = 2 (1 + r)¹⁸⁵
420,000 / 2 = (1 + r)¹⁸⁵
210,000 = (1 + r)¹⁸⁵
¹⁸⁵√210,000 = 1 + r
1.06848 = 1 + r
1.06848 - 1 = r
r = 0.06848 or 6.85%
B) future value = present value (1 + rate)ⁿ
3,158,000 = 420,000 (1 + r)⁴⁶
3,158,000 / 420,000 = (1 + r)⁴⁶
7.519 = (1 + r)⁴⁶
⁴⁶√7.519 = 1 + r
1.04483 = 1 + r
1.04483 - 1 = r
r = 0.04483 or 4.48%
C) future value = present value (1 + rate)ⁿ
3,158,000 = 2 (1 + r)²³¹
3,158,000 / 2 = (1 + r)²³¹
1,579,000 = (1 + r)²³¹
²³¹√1,579,000 = 1 + r
1.0637 = 1 + r
1.0637 - 1 = r
r = 0.0637 or 6.37%