Finding the Fourth Proportional to 111.33, 153.63 and 78.21

Step by Step Solution

1. Step 1: Write the proportion equation
   111.33 : 153.63 = 78.21 : x
2. Step 2: Convert to fraction form
   111.33/153.63 = 78.21/x
3. Step 3: Cross multiply
   111.33x = 153.63 × 78.21
4. Step 4: Simplify right side
   111.33x = 12,015.40
5. Step 5: Solve for x
   x = 12,015.40/111.33
6. Step 6: Final answer
   x = 107.93