Finding the Fourth Proportional to 91.86, 137.81 and 57.57

Step by Step Solution

1. Step 1: Write the proportion equation
   91.86 : 137.81 = 57.57 : x
2. Step 2: Convert to fraction form
   91.86/137.81 = 57.57/x
3. Step 3: Cross multiply
   91.86x = 137.81 × 57.57
4. Step 4: Simplify right side
   91.86x = 7,933.72
5. Step 5: Solve for x
   x = 7,933.72/91.86
6. Step 6: Final answer
   x = 86.37