Finding the Fourth Proportional to 101.05, 139.30 and 71.89

Step by Step Solution

1. Step 1: Write the proportion equation
   101.05 : 139.30 = 71.89 : x
2. Step 2: Convert to fraction form
   101.05/139.30 = 71.89/x
3. Step 3: Cross multiply
   101.05x = 139.30 × 71.89
4. Step 4: Simplify right side
   101.05x = 10,014.28
5. Step 5: Solve for x
   x = 10,014.28/101.05
6. Step 6: Final answer
   x = 99.10