Finding the Fourth Proportional to 128.70, 191.82 and 128.50

Step by Step Solution

1. Step 1: Write the proportion equation
   128.70 : 191.82 = 128.50 : x
2. Step 2: Convert to fraction form
   128.70/191.82 = 128.50/x
3. Step 3: Cross multiply
   128.70x = 191.82 × 128.50
4. Step 4: Simplify right side
   128.70x = 24,648.87
5. Step 5: Solve for x
   x = 24,648.87/128.70
6. Step 6: Final answer
   x = 191.52