Finding the Third Proportional to 128,312 and 309,116

Step by Step Solution

1. Step 1: Write the proportion equation
   128,312 : 309,116 = 309,116 : x
2. Step 2: Convert to fraction form
   128,312/309,116 = 309,116/x
3. Step 3: Cross multiply
   128,312x = 309,116 × 309,116
4. Step 4: Simplify right side
   128,312x = 95,552,701,456
5. Step 5: Solve for x
   x = 95,552,701,456/128,312
6. Step 6: Final answer
   x = 744,690.30