Finding the Fourth Proportional to 78.70, 117.78 and 65.12

Step by Step Solution

1. Step 1: Write the proportion equation
   78.70 : 117.78 = 65.12 : x
2. Step 2: Convert to fraction form
   78.70/117.78 = 65.12/x
3. Step 3: Cross multiply
   78.70x = 117.78 × 65.12
4. Step 4: Simplify right side
   78.70x = 7,669.83
5. Step 5: Solve for x
   x = 7,669.83/78.70
6. Step 6: Final answer
   x = 97.46