Finding the Fourth Proportional to 100.94, 139.20 and 89.42

Step by Step Solution

1. Step 1: Write the proportion equation
   100.94 : 139.20 = 89.42 : x
2. Step 2: Convert to fraction form
   100.94/139.20 = 89.42/x
3. Step 3: Cross multiply
   100.94x = 139.20 × 89.42
4. Step 4: Simplify right side
   100.94x = 12,447.26
5. Step 5: Solve for x
   x = 12,447.26/100.94
6. Step 6: Final answer
   x = 123.31