Finding the Fourth Proportional to 72.56, 100.24 and 57.12

Step by Step Solution

1. Step 1: Write the proportion equation
   72.56 : 100.24 = 57.12 : x
2. Step 2: Convert to fraction form
   72.56/100.24 = 57.12/x
3. Step 3: Cross multiply
   72.56x = 100.24 × 57.12
4. Step 4: Simplify right side
   72.56x = 5,725.71
5. Step 5: Solve for x
   x = 5,725.71/72.56
6. Step 6: Final answer
   x = 78.91