Finding the Fourth Proportional to 90.75, 136.18 and 42.09

Step by Step Solution

1. Step 1: Write the proportion equation
   90.75 : 136.18 = 42.09 : x
2. Step 2: Convert to fraction form
   90.75/136.18 = 42.09/x
3. Step 3: Cross multiply
   90.75x = 136.18 × 42.09
4. Step 4: Simplify right side
   90.75x = 5,731.36
5. Step 5: Solve for x
   x = 5,731.36/90.75
6. Step 6: Final answer
   x = 63.15