Finding the Fourth Proportional to 78.79, 118.31 and 71.12

Step by Step Solution

1. Step 1: Write the proportion equation
   78.79 : 118.31 = 71.12 : x
2. Step 2: Convert to fraction form
   78.79/118.31 = 71.12/x
3. Step 3: Cross multiply
   78.79x = 118.31 × 71.12
4. Step 4: Simplify right side
   78.79x = 8,413.72
5. Step 5: Solve for x
   x = 8,413.72/78.79
6. Step 6: Final answer
   x = 106.79