Finding the Fourth Proportional to 143.60, 215.34 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   143.60 : 215.34 = 78.72 : x
2. Step 2: Convert to fraction form
   143.60/215.34 = 78.72/x
3. Step 3: Cross multiply
   143.60x = 215.34 × 78.72
4. Step 4: Simplify right side
   143.60x = 16,951.56
5. Step 5: Solve for x
   x = 16,951.56/143.60
6. Step 6: Final answer
   x = 118.05