Finding the Fourth Proportional to 72.99, 108.86 and 71.78

Step by Step Solution

1. Step 1: Write the proportion equation
   72.99 : 108.86 = 71.78 : x
2. Step 2: Convert to fraction form
   72.99/108.86 = 71.78/x
3. Step 3: Cross multiply
   72.99x = 108.86 × 71.78
4. Step 4: Simplify right side
   72.99x = 7,813.61
5. Step 5: Solve for x
   x = 7,813.61/72.99
6. Step 6: Final answer
   x = 107.05