Finding the Fourth Proportional to 111.57, 153.95 and 89.79

Step by Step Solution

1. Step 1: Write the proportion equation
   111.57 : 153.95 = 89.79 : x
2. Step 2: Convert to fraction form
   111.57/153.95 = 89.79/x
3. Step 3: Cross multiply
   111.57x = 153.95 × 89.79
4. Step 4: Simplify right side
   111.57x = 13,822.72
5. Step 5: Solve for x
   x = 13,822.72/111.57
6. Step 6: Final answer
   x = 123.89