Finding the Fourth Proportional to 78.80, 118.04 and 42.72

Step by Step Solution

1. Step 1: Write the proportion equation
   78.80 : 118.04 = 42.72 : x
2. Step 2: Convert to fraction form
   78.80/118.04 = 42.72/x
3. Step 3: Cross multiply
   78.80x = 118.04 × 42.72
4. Step 4: Simplify right side
   78.80x = 5,042.67
5. Step 5: Solve for x
   x = 5,042.67/78.80
6. Step 6: Final answer
   x = 63.99