Finding the Fourth Proportional to 78.24, 107.31 and 72.57

Step by Step Solution

1. Step 1: Write the proportion equation
   78.24 : 107.31 = 72.57 : x
2. Step 2: Convert to fraction form
   78.24/107.31 = 72.57/x
3. Step 3: Cross multiply
   78.24x = 107.31 × 72.57
4. Step 4: Simplify right side
   78.24x = 7,787.49
5. Step 5: Solve for x
   x = 7,787.49/78.24
6. Step 6: Final answer
   x = 99.53