Finding the Fourth Proportional to 89.88, 123.98 and 57.12

Step by Step Solution

1. Step 1: Write the proportion equation
   89.88 : 123.98 = 57.12 : x
2. Step 2: Convert to fraction form
   89.88/123.98 = 57.12/x
3. Step 3: Cross multiply
   89.88x = 123.98 × 57.12
4. Step 4: Simplify right side
   89.88x = 7,081.74
5. Step 5: Solve for x
   x = 7,081.74/89.88
6. Step 6: Final answer
   x = 78.79