Finding the Fourth Proportional to 143.78, 215.79 and 78.83

Step by Step Solution

1. Step 1: Write the proportion equation
   143.78 : 215.79 = 78.83 : x
2. Step 2: Convert to fraction form
   143.78/215.79 = 78.83/x
3. Step 3: Cross multiply
   143.78x = 215.79 × 78.83
4. Step 4: Simplify right side
   143.78x = 17,010.16
5. Step 5: Solve for x
   x = 17,010.16/143.78
6. Step 6: Final answer
   x = 118.31