Finding the Fourth Proportional to 1,389.12, 1,919.52 and 1,321.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.12 : 1,919.52 = 1,321.64 : x
2. Step 2: Convert to fraction form
   1,389.12/1,919.52 = 1,321.64/x
3. Step 3: Cross multiply
   1,389.12x = 1,919.52 × 1,321.64
4. Step 4: Simplify right side
   1,389.12x = 2,536,914.41
5. Step 5: Solve for x
   x = 2,536,914.41/1,389.12
6. Step 6: Final answer
   x = 1,826.27