Finding the Fourth Proportional to 2,221.32, 3,065.70 and 1,290.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,221.32 : 3,065.70 = 1,290.12 : x
2. Step 2: Convert to fraction form
   2,221.32/3,065.70 = 1,290.12/x
3. Step 3: Cross multiply
   2,221.32x = 3,065.70 × 1,290.12
4. Step 4: Simplify right side
   2,221.32x = 3,955,120.88
5. Step 5: Solve for x
   x = 3,955,120.88/2,221.32
6. Step 6: Final answer
   x = 1,780.53