Finding the Fourth Proportional to 155.82, 215.01 and 90.31

Step by Step Solution

1. Step 1: Write the proportion equation
   155.82 : 215.01 = 90.31 : x
2. Step 2: Convert to fraction form
   155.82/215.01 = 90.31/x
3. Step 3: Cross multiply
   155.82x = 215.01 × 90.31
4. Step 4: Simplify right side
   155.82x = 19,417.55
5. Step 5: Solve for x
   x = 19,417.55/155.82
6. Step 6: Final answer
   x = 124.62