Finding the Fourth Proportional to 100.79, 139.16 and 89.86

Step by Step Solution

1. Step 1: Write the proportion equation
   100.79 : 139.16 = 89.86 : x
2. Step 2: Convert to fraction form
   100.79/139.16 = 89.86/x
3. Step 3: Cross multiply
   100.79x = 139.16 × 89.86
4. Step 4: Simplify right side
   100.79x = 12,504.57
5. Step 5: Solve for x
   x = 12,504.57/100.79
6. Step 6: Final answer
   x = 124.06