Finding the Third Proportional to 215,790 and 323,688.75

Step by Step Solution

1. Step 1: Write the proportion equation
   215,790 : 323,688.75 = 323,688.75 : x
2. Step 2: Convert to fraction form
   215,790/323,688.75 = 323,688.75/x
3. Step 3: Cross multiply
   215,790x = 323,688.75 × 323,688.75
4. Step 4: Simplify right side
   215,790x = 104,774,406,876.56
5. Step 5: Solve for x
   x = 104,774,406,876.56/215,790
6. Step 6: Final answer
   x = 485,538.75