Finding the Fourth Proportional to 72.31, 108.50 and 72.09

Step by Step Solution

1. Step 1: Write the proportion equation
   72.31 : 108.50 = 72.09 : x
2. Step 2: Convert to fraction form
   72.31/108.50 = 72.09/x
3. Step 3: Cross multiply
   72.31x = 108.50 × 72.09
4. Step 4: Simplify right side
   72.31x = 7,821.77
5. Step 5: Solve for x
   x = 7,821.77/72.31
6. Step 6: Final answer
   x = 108.17