Finding the Fourth Proportional to 111.21, 153.42 and 71.86

Step by Step Solution

1. Step 1: Write the proportion equation
   111.21 : 153.42 = 71.86 : x
2. Step 2: Convert to fraction form
   111.21/153.42 = 71.86/x
3. Step 3: Cross multiply
   111.21x = 153.42 × 71.86
4. Step 4: Simplify right side
   111.21x = 11,023.81
5. Step 5: Solve for x
   x = 11,023.81/111.21
6. Step 6: Final answer
   x = 99.12