Finding the Fourth Proportional to 1,320.89, 1,980.53 and 909.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,320.89 : 1,980.53 = 909.57 : x
2. Step 2: Convert to fraction form
   1,320.89/1,980.53 = 909.57/x
3. Step 3: Cross multiply
   1,320.89x = 1,980.53 × 909.57
4. Step 4: Simplify right side
   1,320.89x = 1,801,416.22
5. Step 5: Solve for x
   x = 1,801,416.22/1,320.89
6. Step 6: Final answer
   x = 1,363.79