Finding the Fourth Proportional to 100.89, 139.28 and 76.13

Step by Step Solution

1. Step 1: Write the proportion equation
   100.89 : 139.28 = 76.13 : x
2. Step 2: Convert to fraction form
   100.89/139.28 = 76.13/x
3. Step 3: Cross multiply
   100.89x = 139.28 × 76.13
4. Step 4: Simplify right side
   100.89x = 10,603.39
5. Step 5: Solve for x
   x = 10,603.39/100.89
6. Step 6: Final answer
   x = 105.10