Finding the Fourth Proportional to 85.98, 128.03 and 82.91

Step by Step Solution

1. Step 1: Write the proportion equation
   85.98 : 128.03 = 82.91 : x
2. Step 2: Convert to fraction form
   85.98/128.03 = 82.91/x
3. Step 3: Cross multiply
   85.98x = 128.03 × 82.91
4. Step 4: Simplify right side
   85.98x = 10,614.53
5. Step 5: Solve for x
   x = 10,614.53/85.98
6. Step 6: Final answer
   x = 123.45