Finding the Fourth Proportional to 111.87, 168.50 and 102.15

Step by Step Solution

1. Step 1: Write the proportion equation
   111.87 : 168.50 = 102.15 : x
2. Step 2: Convert to fraction form
   111.87/168.50 = 102.15/x
3. Step 3: Cross multiply
   111.87x = 168.50 × 102.15
4. Step 4: Simplify right side
   111.87x = 17,212.53
5. Step 5: Solve for x
   x = 17,212.53/111.87
6. Step 6: Final answer
   x = 153.86