Finding the Fourth Proportional to 78.76, 117.98 and 61.72

Step by Step Solution

1. Step 1: Write the proportion equation
   78.76 : 117.98 = 61.72 : x
2. Step 2: Convert to fraction form
   78.76/117.98 = 61.72/x
3. Step 3: Cross multiply
   78.76x = 117.98 × 61.72
4. Step 4: Simplify right side
   78.76x = 7,281.73
5. Step 5: Solve for x
   x = 7,281.73/78.76
6. Step 6: Final answer
   x = 92.45