Finding the Fourth Proportional to 101.22, 139.42 and 90.86

Step by Step Solution

1. Step 1: Write the proportion equation
   101.22 : 139.42 = 90.86 : x
2. Step 2: Convert to fraction form
   101.22/139.42 = 90.86/x
3. Step 3: Cross multiply
   101.22x = 139.42 × 90.86
4. Step 4: Simplify right side
   101.22x = 12,667.12
5. Step 5: Solve for x
   x = 12,667.12/101.22
6. Step 6: Final answer
   x = 125.15