Finding the Fourth Proportional to 128.07, 176.72 and 72.06

Step by Step Solution

1. Step 1: Write the proportion equation
   128.07 : 176.72 = 72.06 : x
2. Step 2: Convert to fraction form
   128.07/176.72 = 72.06/x
3. Step 3: Cross multiply
   128.07x = 176.72 × 72.06
4. Step 4: Simplify right side
   128.07x = 12,734.16
5. Step 5: Solve for x
   x = 12,734.16/128.07
6. Step 6: Final answer
   x = 99.43