Finding the Fourth Proportional to 78.78, 118.14 and 42.78

Step by Step Solution

1. Step 1: Write the proportion equation
   78.78 : 118.14 = 42.78 : x
2. Step 2: Convert to fraction form
   78.78/118.14 = 42.78/x
3. Step 3: Cross multiply
   78.78x = 118.14 × 42.78
4. Step 4: Simplify right side
   78.78x = 5,054.03
5. Step 5: Solve for x
   x = 5,054.03/78.78
6. Step 6: Final answer
   x = 64.15