Finding the Fourth Proportional to 1,309.20, 1,806.72 and 719.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,309.20 : 1,806.72 = 719.76 : x
2. Step 2: Convert to fraction form
   1,309.20/1,806.72 = 719.76/x
3. Step 3: Cross multiply
   1,309.20x = 1,806.72 × 719.76
4. Step 4: Simplify right side
   1,309.20x = 1,300,404.79
5. Step 5: Solve for x
   x = 1,300,404.79/1,309.20
6. Step 6: Final answer
   x = 993.28