Finding the Third Proportional to 261,331.50 and 390,978

Step by Step Solution

1. Step 1: Write the proportion equation
   261,331.50 : 390,978 = 390,978 : x
2. Step 2: Convert to fraction form
   261,331.50/390,978 = 390,978/x
3. Step 3: Cross multiply
   261,331.50x = 390,978 × 390,978
4. Step 4: Simplify right side
   261,331.50x = 152,863,796,484
5. Step 5: Solve for x
   x = 152,863,796,484/261,331.50
6. Step 6: Final answer
   x = 584,942.10