Finding the Fourth Proportional to 91.94, 137.89 and 57.72

Step by Step Solution

1. Step 1: Write the proportion equation
   91.94 : 137.89 = 57.72 : x
2. Step 2: Convert to fraction form
   91.94/137.89 = 57.72/x
3. Step 3: Cross multiply
   91.94x = 137.89 × 57.72
4. Step 4: Simplify right side
   91.94x = 7,959.01
5. Step 5: Solve for x
   x = 7,959.01/91.94
6. Step 6: Final answer
   x = 86.57