Finding the Fourth Proportional to 101.43, 139.82 and 78.21

Step by Step Solution

1. Step 1: Write the proportion equation
   101.43 : 139.82 = 78.21 : x
2. Step 2: Convert to fraction form
   101.43/139.82 = 78.21/x
3. Step 3: Cross multiply
   101.43x = 139.82 × 78.21
4. Step 4: Simplify right side
   101.43x = 10,935.32
5. Step 5: Solve for x
   x = 10,935.32/101.43
6. Step 6: Final answer
   x = 107.81