Finding the Third Proportional to 312,840.50 and 687,889

Step by Step Solution

1. Step 1: Write the proportion equation
   312,840.50 : 687,889 = 687,889 : x
2. Step 2: Convert to fraction form
   312,840.50/687,889 = 687,889/x
3. Step 3: Cross multiply
   312,840.50x = 687,889 × 687,889
4. Step 4: Simplify right side
   312,840.50x = 473,191,276,321
5. Step 5: Solve for x
   x = 473,191,276,321/312,840.50
6. Step 6: Final answer
   x = 1,512,563.99