Finding the Fourth Proportional to 85.81, 127.83 and 83.78

Step by Step Solution

1. Step 1: Write the proportion equation
   85.81 : 127.83 = 83.78 : x
2. Step 2: Convert to fraction form
   85.81/127.83 = 83.78/x
3. Step 3: Cross multiply
   85.81x = 127.83 × 83.78
4. Step 4: Simplify right side
   85.81x = 10,710.00
5. Step 5: Solve for x
   x = 10,710.00/85.81
6. Step 6: Final answer
   x = 124.81