Finding the Fourth Proportional to 72.20, 109.00 and 71.80

Step by Step Solution

1. Step 1: Write the proportion equation
   72.20 : 109.00 = 71.80 : x
2. Step 2: Convert to fraction form
   72.20/109.00 = 71.80/x
3. Step 3: Cross multiply
   72.20x = 109.00 × 71.80
4. Step 4: Simplify right side
   72.20x = 7,825.61
5. Step 5: Solve for x
   x = 7,825.61/72.20
6. Step 6: Final answer
   x = 108.38