Finding the Fourth Proportional to 100.50, 138.69 and 54.50

Step by Step Solution

1. Step 1: Write the proportion equation
   100.50 : 138.69 = 54.50 : x
2. Step 2: Convert to fraction form
   100.50/138.69 = 54.50/x
3. Step 3: Cross multiply
   100.50x = 138.69 × 54.50
4. Step 4: Simplify right side
   100.50x = 7,558.61
5. Step 5: Solve for x
   x = 7,558.61/100.50
6. Step 6: Final answer
   x = 75.21