Finding the Fourth Proportional to 89.81, 123.96 and 57.10

Step by Step Solution

1. Step 1: Write the proportion equation
   89.81 : 123.96 = 57.10 : x
2. Step 2: Convert to fraction form
   89.81/123.96 = 57.10/x
3. Step 3: Cross multiply
   89.81x = 123.96 × 57.10
4. Step 4: Simplify right side
   89.81x = 7,077.83
5. Step 5: Solve for x
   x = 7,077.83/89.81
6. Step 6: Final answer
   x = 78.81