Finding the Fourth Proportional to 89.91, 123.30 and 87.30

Step by Step Solution

1. Step 1: Write the proportion equation
   89.91 : 123.30 = 87.30 : x
2. Step 2: Convert to fraction form
   89.91/123.30 = 87.30/x
3. Step 3: Cross multiply
   89.91x = 123.30 × 87.30
4. Step 4: Simplify right side
   89.91x = 10,764.09
5. Step 5: Solve for x
   x = 10,764.09/89.91
6. Step 6: Final answer
   x = 119.72