Finding the Fourth Proportional to 72.18, 99.63 and 53.79

Step by Step Solution

1. Step 1: Write the proportion equation
   72.18 : 99.63 = 53.79 : x
2. Step 2: Convert to fraction form
   72.18/99.63 = 53.79/x
3. Step 3: Cross multiply
   72.18x = 99.63 × 53.79
4. Step 4: Simplify right side
   72.18x = 5,359.10
5. Step 5: Solve for x
   x = 5,359.10/72.18
6. Step 6: Final answer
   x = 74.25