Finding the Fourth Proportional to 78.76, 118.24 and 42.72

Step by Step Solution

1. Step 1: Write the proportion equation
   78.76 : 118.24 = 42.72 : x
2. Step 2: Convert to fraction form
   78.76/118.24 = 42.72/x
3. Step 3: Cross multiply
   78.76x = 118.24 × 42.72
4. Step 4: Simplify right side
   78.76x = 5,051.21
5. Step 5: Solve for x
   x = 5,051.21/78.76
6. Step 6: Final answer
   x = 64.13