Finding the Fourth Proportional to 69.78, 104.71 and 56.31

Step by Step Solution

1. Step 1: Write the proportion equation
   69.78 : 104.71 = 56.31 : x
2. Step 2: Convert to fraction form
   69.78/104.71 = 56.31/x
3. Step 3: Cross multiply
   69.78x = 104.71 × 56.31
4. Step 4: Simplify right side
   69.78x = 5,896.22
5. Step 5: Solve for x
   x = 5,896.22/69.78
6. Step 6: Final answer
   x = 84.50