Finding the Fourth Proportional to 100,308.78, 138,424.23 and 54,985.50

Step by Step Solution

1. Step 1: Write the proportion equation
   100,308.78 : 138,424.23 = 54,985.50 : x
2. Step 2: Convert to fraction form
   100,308.78/138,424.23 = 54,985.50/x
3. Step 3: Cross multiply
   100,308.78x = 138,424.23 × 54,985.50
4. Step 4: Simplify right side
   100,308.78x = 7,611,325,498.67
5. Step 5: Solve for x
   x = 7,611,325,498.67/100,308.78
6. Step 6: Final answer
   x = 75,878.96