Finding the Fourth Proportional to 91.76, 137.77 and 77.31

Step by Step Solution

1. Step 1: Write the proportion equation
   91.76 : 137.77 = 77.31 : x
2. Step 2: Convert to fraction form
   91.76/137.77 = 77.31/x
3. Step 3: Cross multiply
   91.76x = 137.77 × 77.31
4. Step 4: Simplify right side
   91.76x = 10,650.81
5. Step 5: Solve for x
   x = 10,650.81/91.76
6. Step 6: Final answer
   x = 116.08