Finding the Fourth Proportional to 89.20, 123.12 and 61.57

Step by Step Solution

1. Step 1: Write the proportion equation
   89.20 : 123.12 = 61.57 : x
2. Step 2: Convert to fraction form
   89.20/123.12 = 61.57/x
3. Step 3: Cross multiply
   89.20x = 123.12 × 61.57
4. Step 4: Simplify right side
   89.20x = 7,580.50
5. Step 5: Solve for x
   x = 7,580.50/89.20
6. Step 6: Final answer
   x = 84.98