Finding the Fourth Proportional to 86.91, 119.82 and 72.17

Step by Step Solution

1. Step 1: Write the proportion equation
   86.91 : 119.82 = 72.17 : x
2. Step 2: Convert to fraction form
   86.91/119.82 = 72.17/x
3. Step 3: Cross multiply
   86.91x = 119.82 × 72.17
4. Step 4: Simplify right side
   86.91x = 8,647.53
5. Step 5: Solve for x
   x = 8,647.53/86.91
6. Step 6: Final answer
   x = 99.50