Finding the Fourth Proportional to 1,225.62, 1,690.72 and 721.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,225.62 : 1,690.72 = 721.12 : x
2. Step 2: Convert to fraction form
   1,225.62/1,690.72 = 721.12/x
3. Step 3: Cross multiply
   1,225.62x = 1,690.72 × 721.12
4. Step 4: Simplify right side
   1,225.62x = 1,219,212.01
5. Step 5: Solve for x
   x = 1,219,212.01/1,225.62
6. Step 6: Final answer
   x = 994.77