Finding the Third Proportional to 128,310 and 309,111

Step by Step Solution

1. Step 1: Write the proportion equation
   128,310 : 309,111 = 309,111 : x
2. Step 2: Convert to fraction form
   128,310/309,111 = 309,111/x
3. Step 3: Cross multiply
   128,310x = 309,111 × 309,111
4. Step 4: Simplify right side
   128,310x = 95,549,610,321
5. Step 5: Solve for x
   x = 95,549,610,321/128,310
6. Step 6: Final answer
   x = 744,677.81