Finding the Fourth Proportional to 100.32, 138.18 and 78.42

Step by Step Solution

1. Step 1: Write the proportion equation
   100.32 : 138.18 = 78.42 : x
2. Step 2: Convert to fraction form
   100.32/138.18 = 78.42/x
3. Step 3: Cross multiply
   100.32x = 138.18 × 78.42
4. Step 4: Simplify right side
   100.32x = 10,836.08
5. Step 5: Solve for x
   x = 10,836.08/100.32
6. Step 6: Final answer
   x = 108.02