Finding the Fourth Proportional to 78.89, 117.71 and 69.77

Step by Step Solution

1. Step 1: Write the proportion equation
   78.89 : 117.71 = 69.77 : x
2. Step 2: Convert to fraction form
   78.89/117.71 = 69.77/x
3. Step 3: Cross multiply
   78.89x = 117.71 × 69.77
4. Step 4: Simplify right side
   78.89x = 8,212.83
5. Step 5: Solve for x
   x = 8,212.83/78.89
6. Step 6: Final answer
   x = 104.11