Finding the Fourth Proportional to 76.80, 105.98 and 45.72

Step by Step Solution

1. Step 1: Write the proportion equation
   76.80 : 105.98 = 45.72 : x
2. Step 2: Convert to fraction form
   76.80/105.98 = 45.72/x
3. Step 3: Cross multiply
   76.80x = 105.98 × 45.72
4. Step 4: Simplify right side
   76.80x = 4,845.41
5. Step 5: Solve for x
   x = 4,845.41/76.80
6. Step 6: Final answer
   x = 63.09