Finding the Fourth Proportional to 143.91, 215.72 and 78.83

Step by Step Solution

1. Step 1: Write the proportion equation
   143.91 : 215.72 = 78.83 : x
2. Step 2: Convert to fraction form
   143.91/215.72 = 78.83/x
3. Step 3: Cross multiply
   143.91x = 215.72 × 78.83
4. Step 4: Simplify right side
   143.91x = 17,003.73
5. Step 5: Solve for x
   x = 17,003.73/143.91
6. Step 6: Final answer
   x = 118.16