Finding the Fourth Proportional to 72.78, 100.55 and 51.05

Step by Step Solution

1. Step 1: Write the proportion equation
   72.78 : 100.55 = 51.05 : x
2. Step 2: Convert to fraction form
   72.78/100.55 = 51.05/x
3. Step 3: Cross multiply
   72.78x = 100.55 × 51.05
4. Step 4: Simplify right side
   72.78x = 5,132.70
5. Step 5: Solve for x
   x = 5,132.70/72.78
6. Step 6: Final answer
   x = 70.52