Finding the Fourth Proportional to 90.42, 134.94 and 78.84

Step by Step Solution

1. Step 1: Write the proportion equation
   90.42 : 134.94 = 78.84 : x
2. Step 2: Convert to fraction form
   90.42/134.94 = 78.84/x
3. Step 3: Cross multiply
   90.42x = 134.94 × 78.84
4. Step 4: Simplify right side
   90.42x = 10,638.67
5. Step 5: Solve for x
   x = 10,638.67/90.42
6. Step 6: Final answer
   x = 117.66