Finding the Fourth Proportional to 156.89, 216.50 and 90.50

Step by Step Solution

1. Step 1: Write the proportion equation
   156.89 : 216.50 = 90.50 : x
2. Step 2: Convert to fraction form
   156.89/216.50 = 90.50/x
3. Step 3: Cross multiply
   156.89x = 216.50 × 90.50
4. Step 4: Simplify right side
   156.89x = 19,591.72
5. Step 5: Solve for x
   x = 19,591.72/156.89
6. Step 6: Final answer
   x = 124.88