Finding the Fourth Proportional to 100.08, 138.06 and 78.30

Step by Step Solution

1. Step 1: Write the proportion equation
   100.08 : 138.06 = 78.30 : x
2. Step 2: Convert to fraction form
   100.08/138.06 = 78.30/x
3. Step 3: Cross multiply
   100.08x = 138.06 × 78.30
4. Step 4: Simplify right side
   100.08x = 10,810.10
5. Step 5: Solve for x
   x = 10,810.10/100.08
6. Step 6: Final answer
   x = 108.01