Finding the Fourth Proportional to 128.91, 177.89 and 70.69

Step by Step Solution

1. Step 1: Write the proportion equation
   128.91 : 177.89 = 70.69 : x
2. Step 2: Convert to fraction form
   128.91/177.89 = 70.69/x
3. Step 3: Cross multiply
   128.91x = 177.89 × 70.69
4. Step 4: Simplify right side
   128.91x = 12,574.78
5. Step 5: Solve for x
   x = 12,574.78/128.91
6. Step 6: Final answer
   x = 97.55