Finding the Fourth Proportional to 1,428.43, 1,970.95 and 807.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.43 : 1,970.95 = 807.31 : x
2. Step 2: Convert to fraction form
   1,428.43/1,970.95 = 807.31/x
3. Step 3: Cross multiply
   1,428.43x = 1,970.95 × 807.31
4. Step 4: Simplify right side
   1,428.43x = 1,591,167.64
5. Step 5: Solve for x
   x = 1,591,167.64/1,428.43
6. Step 6: Final answer
   x = 1,113.93