Finding the Fourth Proportional to 124.55, 171.90 and 72.10

Step by Step Solution

1. Step 1: Write the proportion equation
   124.55 : 171.90 = 72.10 : x
2. Step 2: Convert to fraction form
   124.55/171.90 = 72.10/x
3. Step 3: Cross multiply
   124.55x = 171.90 × 72.10
4. Step 4: Simplify right side
   124.55x = 12,392.77
5. Step 5: Solve for x
   x = 12,392.77/124.55
6. Step 6: Final answer
   x = 99.50