Finding the Third Proportional to 261,256.50 and 390,870.75

Step by Step Solution

1. Step 1: Write the proportion equation
   261,256.50 : 390,870.75 = 390,870.75 : x
2. Step 2: Convert to fraction form
   261,256.50/390,870.75 = 390,870.75/x
3. Step 3: Cross multiply
   261,256.50x = 390,870.75 × 390,870.75
4. Step 4: Simplify right side
   261,256.50x = 152,779,943,205.56
5. Step 5: Solve for x
   x = 152,779,943,205.56/261,256.50
6. Step 6: Final answer
   x = 584,789.06