Let x be the amount (in dollars) invested in fund B at 6% interest. Then investment in fund A is 3x dollars, at 3% interest. Total interest is the sum of partial interests 0.03*(3x) + 0.06*x = 1350. Simplify and solve for x 0.09x + 0.06x = 1350, 0.15x = 1350, x == 9000 dollars. The amount invested in fund B was $9000. ANSWER