Finding the Fourth Proportional to 89.50, 123.40 and 72.09

Step by Step Solution

1. Step 1: Write the proportion equation
   89.50 : 123.40 = 72.09 : x
2. Step 2: Convert to fraction form
   89.50/123.40 = 72.09/x
3. Step 3: Cross multiply
   89.50x = 123.40 × 72.09
4. Step 4: Simplify right side
   89.50x = 8,895.91
5. Step 5: Solve for x
   x = 8,895.91/89.50
6. Step 6: Final answer
   x = 99.40