Finding the Fourth Proportional to 85.82, 127.79 and 78.56

Step by Step Solution

1. Step 1: Write the proportion equation
   85.82 : 127.79 = 78.56 : x
2. Step 2: Convert to fraction form
   85.82/127.79 = 78.56/x
3. Step 3: Cross multiply
   85.82x = 127.79 × 78.56
4. Step 4: Simplify right side
   85.82x = 10,039.18
5. Step 5: Solve for x
   x = 10,039.18/85.82
6. Step 6: Final answer
   x = 116.98