Finding the Fourth Proportional to 89.60, 123.72 and 77.99

Step by Step Solution

1. Step 1: Write the proportion equation
   89.60 : 123.72 = 77.99 : x
2. Step 2: Convert to fraction form
   89.60/123.72 = 77.99/x
3. Step 3: Cross multiply
   89.60x = 123.72 × 77.99
4. Step 4: Simplify right side
   89.60x = 9,648.92
5. Step 5: Solve for x
   x = 9,648.92/89.60
6. Step 6: Final answer
   x = 107.69