Finding the Fourth Proportional to 105.60, 158.05 and 90.42

Step by Step Solution

1. Step 1: Write the proportion equation
   105.60 : 158.05 = 90.42 : x
2. Step 2: Convert to fraction form
   105.60/158.05 = 90.42/x
3. Step 3: Cross multiply
   105.60x = 158.05 × 90.42
4. Step 4: Simplify right side
   105.60x = 14,290.88
5. Step 5: Solve for x
   x = 14,290.88/105.60
6. Step 6: Final answer
   x = 135.33