Finding the Third Proportional to 128,820 and 189,499.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128,820 : 189,499.50 = 189,499.50 : x
2. Step 2: Convert to fraction form
   128,820/189,499.50 = 189,499.50/x
3. Step 3: Cross multiply
   128,820x = 189,499.50 × 189,499.50
4. Step 4: Simplify right side
   128,820x = 35,910,060,500.25
5. Step 5: Solve for x
   x = 35,910,060,500.25/128,820
6. Step 6: Final answer
   x = 278,761.53