Finding the Fourth Proportional to 101.10, 139.50 and 88.78

Step by Step Solution

1. Step 1: Write the proportion equation
   101.10 : 139.50 = 88.78 : x
2. Step 2: Convert to fraction form
   101.10/139.50 = 88.78/x
3. Step 3: Cross multiply
   101.10x = 139.50 × 88.78
4. Step 4: Simplify right side
   101.10x = 12,384.81
5. Step 5: Solve for x
   x = 12,384.81/101.10
6. Step 6: Final answer
   x = 122.50