Finding the Fourth Proportional to 100.77, 139.27 and 86.95

Step by Step Solution

1. Step 1: Write the proportion equation
   100.77 : 139.27 = 86.95 : x
2. Step 2: Convert to fraction form
   100.77/139.27 = 86.95/x
3. Step 3: Cross multiply
   100.77x = 139.27 × 86.95
4. Step 4: Simplify right side
   100.77x = 12,109.25
5. Step 5: Solve for x
   x = 12,109.25/100.77
6. Step 6: Final answer
   x = 120.17