Finding the Fourth Proportional to 101.50, 139.77 and 89.15

Step by Step Solution

1. Step 1: Write the proportion equation
   101.50 : 139.77 = 89.15 : x
2. Step 2: Convert to fraction form
   101.50/139.77 = 89.15/x
3. Step 3: Cross multiply
   101.50x = 139.77 × 89.15
4. Step 4: Simplify right side
   101.50x = 12,460.50
5. Step 5: Solve for x
   x = 12,460.50/101.50
6. Step 6: Final answer
   x = 122.76