Finding the Fourth Proportional to 100.89, 139.05 and 76.32

Step by Step Solution

1. Step 1: Write the proportion equation
   100.89 : 139.05 = 76.32 : x
2. Step 2: Convert to fraction form
   100.89/139.05 = 76.32/x
3. Step 3: Cross multiply
   100.89x = 139.05 × 76.32
4. Step 4: Simplify right side
   100.89x = 10,612.30
5. Step 5: Solve for x
   x = 10,612.30/100.89
6. Step 6: Final answer
   x = 105.19