Finding the Fourth Proportional to 89.63, 123.69 and 56.43

Step by Step Solution

1. Step 1: Write the proportion equation
   89.63 : 123.69 = 56.43 : x
2. Step 2: Convert to fraction form
   89.63/123.69 = 56.43/x
3. Step 3: Cross multiply
   89.63x = 123.69 × 56.43
4. Step 4: Simplify right side
   89.63x = 6,979.83
5. Step 5: Solve for x
   x = 6,979.83/89.63
6. Step 6: Final answer
   x = 77.88