Finding the Fourth Proportional to 72.80, 100.54 and 71.99

Step by Step Solution

1. Step 1: Write the proportion equation
   72.80 : 100.54 = 71.99 : x
2. Step 2: Convert to fraction form
   72.80/100.54 = 71.99/x
3. Step 3: Cross multiply
   72.80x = 100.54 × 71.99
4. Step 4: Simplify right side
   72.80x = 7,237.87
5. Step 5: Solve for x
   x = 7,237.87/72.80
6. Step 6: Final answer
   x = 99.42