Finding the Fourth Proportional to 78.31, 107.88 and 72.55

Step by Step Solution

1. Step 1: Write the proportion equation
   78.31 : 107.88 = 72.55 : x
2. Step 2: Convert to fraction form
   78.31/107.88 = 72.55/x
3. Step 3: Cross multiply
   78.31x = 107.88 × 72.55
4. Step 4: Simplify right side
   78.31x = 7,826.69
5. Step 5: Solve for x
   x = 7,826.69/78.31
6. Step 6: Final answer
   x = 99.95