Finding the Fourth Proportional to 128.00, 176.61 and 78.89

Step by Step Solution

1. Step 1: Write the proportion equation
   128.00 : 176.61 = 78.89 : x
2. Step 2: Convert to fraction form
   128.00/176.61 = 78.89/x
3. Step 3: Cross multiply
   128.00x = 176.61 × 78.89
4. Step 4: Simplify right side
   128.00x = 13,933.20
5. Step 5: Solve for x
   x = 13,933.20/128.00
6. Step 6: Final answer
   x = 108.85