Finding the Fourth Proportional to 92.89, 138.56 and 91.72

Step by Step Solution

1. Step 1: Write the proportion equation
   92.89 : 138.56 = 91.72 : x
2. Step 2: Convert to fraction form
   92.89/138.56 = 91.72/x
3. Step 3: Cross multiply
   92.89x = 138.56 × 91.72
4. Step 4: Simplify right side
   92.89x = 12,708.72
5. Step 5: Solve for x
   x = 12,708.72/92.89
6. Step 6: Final answer
   x = 136.81