Finding the Fourth Proportional to 128.21, 176.73 and 100.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128.21 : 176.73 = 100.50 : x
2. Step 2: Convert to fraction form
   128.21/176.73 = 100.50/x
3. Step 3: Cross multiply
   128.21x = 176.73 × 100.50
4. Step 4: Simplify right side
   128.21x = 17,761.37
5. Step 5: Solve for x
   x = 17,761.37/128.21
6. Step 6: Final answer
   x = 138.54