Finding the Fourth Proportional to 1,429.61, 1,972.82 and 840.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,429.61 : 1,972.82 = 840.20 : x
2. Step 2: Convert to fraction form
   1,429.61/1,972.82 = 840.20/x
3. Step 3: Cross multiply
   1,429.61x = 1,972.82 × 840.20
4. Step 4: Simplify right side
   1,429.61x = 1,657,555.60
5. Step 5: Solve for x
   x = 1,657,555.60/1,429.61
6. Step 6: Final answer
   x = 1,159.45