Finding the Fourth Proportional to 78.83, 108.79 and 76.31

Step by Step Solution

1. Step 1: Write the proportion equation
   78.83 : 108.79 = 76.31 : x
2. Step 2: Convert to fraction form
   78.83/108.79 = 76.31/x
3. Step 3: Cross multiply
   78.83x = 108.79 × 76.31
4. Step 4: Simplify right side
   78.83x = 8,301.03
5. Step 5: Solve for x
   x = 8,301.03/78.83
6. Step 6: Final answer
   x = 105.31