Finding the Fourth Proportional to 102.78, 153.39 and 100.05

Step by Step Solution

1. Step 1: Write the proportion equation
   102.78 : 153.39 = 100.05 : x
2. Step 2: Convert to fraction form
   102.78/153.39 = 100.05/x
3. Step 3: Cross multiply
   102.78x = 153.39 × 100.05
4. Step 4: Simplify right side
   102.78x = 15,346.69
5. Step 5: Solve for x
   x = 15,346.69/102.78
6. Step 6: Final answer
   x = 149.31