Finding the Fourth Proportional to 1,665.86, 2,499.90 and 691.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,665.86 : 2,499.90 = 691.96 : x
2. Step 2: Convert to fraction form
   1,665.86/2,499.90 = 691.96/x
3. Step 3: Cross multiply
   1,665.86x = 2,499.90 × 691.96
4. Step 4: Simplify right side
   1,665.86x = 1,729,814.84
5. Step 5: Solve for x
   x = 1,729,814.84/1,665.86
6. Step 6: Final answer
   x = 1,038.39