Finding the Third Proportional to 455.78 and 698.86

Step by Step Solution

1. Step 1: Write the proportion equation
   455.78 : 698.86 = 698.86 : x
2. Step 2: Convert to fraction form
   455.78/698.86 = 698.86/x
3. Step 3: Cross multiply
   455.78x = 698.86 × 698.86
4. Step 4: Simplify right side
   455.78x = 488,408.52
5. Step 5: Solve for x
   x = 488,408.52/455.78
6. Step 6: Final answer
   x = 1,071.58