Finding the Fourth Proportional to 1,139.95, 1,572.96 and 720.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,139.95 : 1,572.96 = 720.10 : x
2. Step 2: Convert to fraction form
   1,139.95/1,572.96 = 720.10/x
3. Step 3: Cross multiply
   1,139.95x = 1,572.96 × 720.10
4. Step 4: Simplify right side
   1,139.95x = 1,132,688.50
5. Step 5: Solve for x
   x = 1,132,688.50/1,139.95
6. Step 6: Final answer
   x = 993.63