Finding the Fourth Proportional to 128.98, 177.91 and 99.82

Step by Step Solution

1. Step 1: Write the proportion equation
   128.98 : 177.91 = 99.82 : x
2. Step 2: Convert to fraction form
   128.98/177.91 = 99.82/x
3. Step 3: Cross multiply
   128.98x = 177.91 × 99.82
4. Step 4: Simplify right side
   128.98x = 17,758.98
5. Step 5: Solve for x
   x = 17,758.98/128.98
6. Step 6: Final answer
   x = 137.69