Finding the Fourth Proportional to 2,215.77, 3,317.21 and 1,288.50

Step by Step Solution

1. Step 1: Write the proportion equation
   2,215.77 : 3,317.21 = 1,288.50 : x
2. Step 2: Convert to fraction form
   2,215.77/3,317.21 = 1,288.50/x
3. Step 3: Cross multiply
   2,215.77x = 3,317.21 × 1,288.50
4. Step 4: Simplify right side
   2,215.77x = 4,274,225.09
5. Step 5: Solve for x
   x = 4,274,225.09/2,215.77
6. Step 6: Final answer
   x = 1,929.00