Finding the Third Proportional to 156,978 and 221,158

Step by Step Solution

1. Step 1: Write the proportion equation
   156,978 : 221,158 = 221,158 : x
2. Step 2: Convert to fraction form
   156,978/221,158 = 221,158/x
3. Step 3: Cross multiply
   156,978x = 221,158 × 221,158
4. Step 4: Simplify right side
   156,978x = 48,910,860,964
5. Step 5: Solve for x
   x = 48,910,860,964/156,978
6. Step 6: Final answer
   x = 311,577.81