Finding the Fourth Proportional to 128.16, 191.82 and 89.07

Step by Step Solution

1. Step 1: Write the proportion equation
   128.16 : 191.82 = 89.07 : x
2. Step 2: Convert to fraction form
   128.16/191.82 = 89.07/x
3. Step 3: Cross multiply
   128.16x = 191.82 × 89.07
4. Step 4: Simplify right side
   128.16x = 17,085.41
5. Step 5: Solve for x
   x = 17,085.41/128.16
6. Step 6: Final answer
   x = 133.31