Finding the Fourth Proportional to 1,605.50, 2,215.61 and 906.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,605.50 : 2,215.61 = 906.89 : x
2. Step 2: Convert to fraction form
   1,605.50/2,215.61 = 906.89/x
3. Step 3: Cross multiply
   1,605.50x = 2,215.61 × 906.89
4. Step 4: Simplify right side
   1,605.50x = 2,009,310.02
5. Step 5: Solve for x
   x = 2,009,310.02/1,605.50
6. Step 6: Final answer
   x = 1,251.52