Finding the Fourth Proportional to 1,665.86, 2,498.81 and 800.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,665.86 : 2,498.81 = 800.78 : x
2. Step 2: Convert to fraction form
   1,665.86/2,498.81 = 800.78/x
3. Step 3: Cross multiply
   1,665.86x = 2,498.81 × 800.78
4. Step 4: Simplify right side
   1,665.86x = 2,000,980.57
5. Step 5: Solve for x
   x = 2,000,980.57/1,665.86
6. Step 6: Final answer
   x = 1,201.17