Finding the Fourth Proportional to 100.06, 137.89 and 90.12

Step by Step Solution

1. Step 1: Write the proportion equation
   100.06 : 137.89 = 90.12 : x
2. Step 2: Convert to fraction form
   100.06/137.89 = 90.12/x
3. Step 3: Cross multiply
   100.06x = 137.89 × 90.12
4. Step 4: Simplify right side
   100.06x = 12,425.90
5. Step 5: Solve for x
   x = 12,425.90/100.06
6. Step 6: Final answer
   x = 124.19