Finding the Fourth Proportional to 100.99, 139.22 and 74.78

Step by Step Solution

1. Step 1: Write the proportion equation
   100.99 : 139.22 = 74.78 : x
2. Step 2: Convert to fraction form
   100.99/139.22 = 74.78/x
3. Step 3: Cross multiply
   100.99x = 139.22 × 74.78
4. Step 4: Simplify right side
   100.99x = 10,410.18
5. Step 5: Solve for x
   x = 10,410.18/100.99
6. Step 6: Final answer
   x = 103.09