Finding the Third Proportional to 156.78 and 276.86

Step by Step Solution

1. Step 1: Write the proportion equation
   156.78 : 276.86 = 276.86 : x
2. Step 2: Convert to fraction form
   156.78/276.86 = 276.86/x
3. Step 3: Cross multiply
   156.78x = 276.86 × 276.86
4. Step 4: Simplify right side
   156.78x = 76,648.95
5. Step 5: Solve for x
   x = 76,648.95/156.78
6. Step 6: Final answer
   x = 488.90