Finding the Fourth Proportional to 101.31, 139.88 and 85.81

Step by Step Solution

1. Step 1: Write the proportion equation
   101.31 : 139.88 = 85.81 : x
2. Step 2: Convert to fraction form
   101.31/139.88 = 85.81/x
3. Step 3: Cross multiply
   101.31x = 139.88 × 85.81
4. Step 4: Simplify right side
   101.31x = 12,003.10
5. Step 5: Solve for x
   x = 12,003.10/101.31
6. Step 6: Final answer
   x = 118.48