Finding the Fourth Proportional to 1,288.35, 1,777.55 and 916.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.35 : 1,777.55 = 916.29 : x
2. Step 2: Convert to fraction form
   1,288.35/1,777.55 = 916.29/x
3. Step 3: Cross multiply
   1,288.35x = 1,777.55 × 916.29
4. Step 4: Simplify right side
   1,288.35x = 1,628,746.71
5. Step 5: Solve for x
   x = 1,628,746.71/1,288.35
6. Step 6: Final answer
   x = 1,264.21