Finding the Fourth Proportional to 100.69, 139.12 and 88.39

Step by Step Solution

1. Step 1: Write the proportion equation
   100.69 : 139.12 = 88.39 : x
2. Step 2: Convert to fraction form
   100.69/139.12 = 88.39/x
3. Step 3: Cross multiply
   100.69x = 139.12 × 88.39
4. Step 4: Simplify right side
   100.69x = 12,296.77
5. Step 5: Solve for x
   x = 12,296.77/100.69
6. Step 6: Final answer
   x = 122.12