Finding the Fourth Proportional to 89.68, 123.71 and 56.90

Step by Step Solution

1. Step 1: Write the proportion equation
   89.68 : 123.71 = 56.90 : x
2. Step 2: Convert to fraction form
   89.68/123.71 = 56.90/x
3. Step 3: Cross multiply
   89.68x = 123.71 × 56.90
4. Step 4: Simplify right side
   89.68x = 7,039.10
5. Step 5: Solve for x
   x = 7,039.10/89.68
6. Step 6: Final answer
   x = 78.49