Finding the Fourth Proportional to 111.51, 153.85 and 85.30

Step by Step Solution

1. Step 1: Write the proportion equation
   111.51 : 153.85 = 85.30 : x
2. Step 2: Convert to fraction form
   111.51/153.85 = 85.30/x
3. Step 3: Cross multiply
   111.51x = 153.85 × 85.30
4. Step 4: Simplify right side
   111.51x = 13,123.83
5. Step 5: Solve for x
   x = 13,123.83/111.51
6. Step 6: Final answer
   x = 117.69