Finding the Fourth Proportional to 123.72, 170.71 and 80.05

Step by Step Solution

1. Step 1: Write the proportion equation
   123.72 : 170.71 = 80.05 : x
2. Step 2: Convert to fraction form
   123.72/170.71 = 80.05/x
3. Step 3: Cross multiply
   123.72x = 170.71 × 80.05
4. Step 4: Simplify right side
   123.72x = 13,665.34
5. Step 5: Solve for x
   x = 13,665.34/123.72
6. Step 6: Final answer
   x = 110.45