Finding the Fourth Proportional to 105.31, 158.13 and 90.25

Step by Step Solution

1. Step 1: Write the proportion equation
   105.31 : 158.13 = 90.25 : x
2. Step 2: Convert to fraction form
   105.31/158.13 = 90.25/x
3. Step 3: Cross multiply
   105.31x = 158.13 × 90.25
4. Step 4: Simplify right side
   105.31x = 14,271.23
5. Step 5: Solve for x
   x = 14,271.23/105.31
6. Step 6: Final answer
   x = 135.52