Finding the Third Proportional to 286,308 and 420,907.50

Step by Step Solution

1. Step 1: Write the proportion equation
   286,308 : 420,907.50 = 420,907.50 : x
2. Step 2: Convert to fraction form
   286,308/420,907.50 = 420,907.50/x
3. Step 3: Cross multiply
   286,308x = 420,907.50 × 420,907.50
4. Step 4: Simplify right side
   286,308x = 177,163,123,556.25
5. Step 5: Solve for x
   x = 177,163,123,556.25/286,308
6. Step 6: Final answer
   x = 618,785.10