Finding the Fourth Proportional to 90.83, 136.41 and 78.18

Step by Step Solution

1. Step 1: Write the proportion equation
   90.83 : 136.41 = 78.18 : x
2. Step 2: Convert to fraction form
   90.83/136.41 = 78.18/x
3. Step 3: Cross multiply
   90.83x = 136.41 × 78.18
4. Step 4: Simplify right side
   90.83x = 10,664.53
5. Step 5: Solve for x
   x = 10,664.53/90.83
6. Step 6: Final answer
   x = 117.42