Finding the Fourth Proportional to 103.74, 155.31 and 78.17

Step by Step Solution

1. Step 1: Write the proportion equation
   103.74 : 155.31 = 78.17 : x
2. Step 2: Convert to fraction form
   103.74/155.31 = 78.17/x
3. Step 3: Cross multiply
   103.74x = 155.31 × 78.17
4. Step 4: Simplify right side
   103.74x = 12,139.81
5. Step 5: Solve for x
   x = 12,139.81/103.74
6. Step 6: Final answer
   x = 117.02