Finding the Third Proportional to 128,389.50 and 200,356.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,389.50 : 200,356.50 = 200,356.50 : x
2. Step 2: Convert to fraction form
   128,389.50/200,356.50 = 200,356.50/x
3. Step 3: Cross multiply
   128,389.50x = 200,356.50 × 200,356.50
4. Step 4: Simplify right side
   128,389.50x = 40,142,727,092.25
5. Step 5: Solve for x
   x = 40,142,727,092.25/128,389.50
6. Step 6: Final answer
   x = 312,663.63