Finding the Fourth Proportional to 67.20, 100.72 and 51.20

Step by Step Solution

1. Step 1: Write the proportion equation
   67.20 : 100.72 = 51.20 : x
2. Step 2: Convert to fraction form
   67.20/100.72 = 51.20/x
3. Step 3: Cross multiply
   67.20x = 100.72 × 51.20
4. Step 4: Simplify right side
   67.20x = 5,156.86
5. Step 5: Solve for x
   x = 5,156.86/67.20
6. Step 6: Final answer
   x = 76.74