Finding the Fourth Proportional to 1,090.98, 1,505.78 and 717.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,090.98 : 1,505.78 = 717.99 : x
2. Step 2: Convert to fraction form
   1,090.98/1,505.78 = 717.99/x
3. Step 3: Cross multiply
   1,090.98x = 1,505.78 × 717.99
4. Step 4: Simplify right side
   1,090.98x = 1,081,134.69
5. Step 5: Solve for x
   x = 1,081,134.69/1,090.98
6. Step 6: Final answer
   x = 990.98