Finding the Third Proportional to 78,490 and 100,782.50

Step by Step Solution

1. Step 1: Write the proportion equation
   78,490 : 100,782.50 = 100,782.50 : x
2. Step 2: Convert to fraction form
   78,490/100,782.50 = 100,782.50/x
3. Step 3: Cross multiply
   78,490x = 100,782.50 × 100,782.50
4. Step 4: Simplify right side
   78,490x = 10,157,112,306.25
5. Step 5: Solve for x
   x = 10,157,112,306.25/78,490
6. Step 6: Final answer
   x = 129,406.45