Finding the Fourth Proportional to 1,422.40, 1,962.21 and 1,225.57

Step by Step Solution

1. Step 1: Write the proportion equation
   1,422.40 : 1,962.21 = 1,225.57 : x
2. Step 2: Convert to fraction form
   1,422.40/1,962.21 = 1,225.57/x
3. Step 3: Cross multiply
   1,422.40x = 1,962.21 × 1,225.57
4. Step 4: Simplify right side
   1,422.40x = 2,404,825.71
5. Step 5: Solve for x
   x = 2,404,825.71/1,422.40
6. Step 6: Final answer
   x = 1,690.68