Finding the Fourth Proportional to 128.50, 192.48 and 89.98

Step by Step Solution

1. Step 1: Write the proportion equation
   128.50 : 192.48 = 89.98 : x
2. Step 2: Convert to fraction form
   128.50/192.48 = 89.98/x
3. Step 3: Cross multiply
   128.50x = 192.48 × 89.98
4. Step 4: Simplify right side
   128.50x = 17,319.35
5. Step 5: Solve for x
   x = 17,319.35/128.50
6. Step 6: Final answer
   x = 134.78