Finding the Fourth Proportional to 100.82, 139.05 and 69.78

Step by Step Solution

1. Step 1: Write the proportion equation
   100.82 : 139.05 = 69.78 : x
2. Step 2: Convert to fraction form
   100.82/139.05 = 69.78/x
3. Step 3: Cross multiply
   100.82x = 139.05 × 69.78
4. Step 4: Simplify right side
   100.82x = 9,703.50
5. Step 5: Solve for x
   x = 9,703.50/100.82
6. Step 6: Final answer
   x = 96.25