Finding the Fourth Proportional to 1,431.29, 1,978.30 and 1,320.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,431.29 : 1,978.30 = 1,320.57 : x
2. Step 2: Convert to fraction form
   1,431.29/1,978.30 = 1,320.57/x
3. Step 3: Cross multiply
   1,431.29x = 1,978.30 × 1,320.57
4. Step 4: Simplify right side
   1,431.29x = 2,612,481.56
5. Step 5: Solve for x
   x = 2,612,481.56/1,431.29
6. Step 6: Final answer
   x = 1,825.26