Finding the Fourth Proportional to 1,170.80, 1,613.83 and 921.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,170.80 : 1,613.83 = 921.72 : x
2. Step 2: Convert to fraction form
   1,170.80/1,613.83 = 921.72/x
3. Step 3: Cross multiply
   1,170.80x = 1,613.83 × 921.72
4. Step 4: Simplify right side
   1,170.80x = 1,487,494.78
5. Step 5: Solve for x
   x = 1,487,494.78/1,170.80
6. Step 6: Final answer
   x = 1,270.50