Finding the Fourth Proportional to 78.71, 108.32 and 72.09

Step by Step Solution

1. Step 1: Write the proportion equation
   78.71 : 108.32 = 72.09 : x
2. Step 2: Convert to fraction form
   78.71/108.32 = 72.09/x
3. Step 3: Cross multiply
   78.71x = 108.32 × 72.09
4. Step 4: Simplify right side
   78.71x = 7,808.43
5. Step 5: Solve for x
   x = 7,808.43/78.71
6. Step 6: Final answer
   x = 99.21