Finding the Fourth Proportional to 123.72, 170.82 and 99.18

Step by Step Solution

1. Step 1: Write the proportion equation
   123.72 : 170.82 = 99.18 : x
2. Step 2: Convert to fraction form
   123.72/170.82 = 99.18/x
3. Step 3: Cross multiply
   123.72x = 170.82 × 99.18
4. Step 4: Simplify right side
   123.72x = 16,941.93
5. Step 5: Solve for x
   x = 16,941.93/123.72
6. Step 6: Final answer
   x = 136.94