Finding the Fourth Proportional to 111.39, 153.77 and 99.72

Step by Step Solution

1. Step 1: Write the proportion equation
   111.39 : 153.77 = 99.72 : x
2. Step 2: Convert to fraction form
   111.39/153.77 = 99.72/x
3. Step 3: Cross multiply
   111.39x = 153.77 × 99.72
4. Step 4: Simplify right side
   111.39x = 15,333.05
5. Step 5: Solve for x
   x = 15,333.05/111.39
6. Step 6: Final answer
   x = 137.65