Finding the Fourth Proportional to 1,419.70, 2,131.56 and 870.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,419.70 : 2,131.56 = 870.20 : x
2. Step 2: Convert to fraction form
   1,419.70/2,131.56 = 870.20/x
3. Step 3: Cross multiply
   1,419.70x = 2,131.56 × 870.20
4. Step 4: Simplify right side
   1,419.70x = 1,854,883.51
5. Step 5: Solve for x
   x = 1,854,883.51/1,419.70
6. Step 6: Final answer
   x = 1,306.53