Finding the Fourth Proportional to 91.98, 137.98 and 76.88

Step by Step Solution

1. Step 1: Write the proportion equation
   91.98 : 137.98 = 76.88 : x
2. Step 2: Convert to fraction form
   91.98/137.98 = 76.88/x
3. Step 3: Cross multiply
   91.98x = 137.98 × 76.88
4. Step 4: Simplify right side
   91.98x = 10,607.90
5. Step 5: Solve for x
   x = 10,607.90/91.98
6. Step 6: Final answer
   x = 115.33