Finding the Fourth Proportional to 128.51, 177.33 and 72.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128.51 : 177.33 = 72.50 : x
2. Step 2: Convert to fraction form
   128.51/177.33 = 72.50/x
3. Step 3: Cross multiply
   128.51x = 177.33 × 72.50
4. Step 4: Simplify right side
   128.51x = 12,855.60
5. Step 5: Solve for x
   x = 12,855.60/128.51
6. Step 6: Final answer
   x = 100.03