Finding the Fourth Proportional to 1,290.47, 1,782.32 and 870.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.47 : 1,782.32 = 870.10 : x
2. Step 2: Convert to fraction form
   1,290.47/1,782.32 = 870.10/x
3. Step 3: Cross multiply
   1,290.47x = 1,782.32 × 870.10
4. Step 4: Simplify right side
   1,290.47x = 1,550,796.63
5. Step 5: Solve for x
   x = 1,550,796.63/1,290.47
6. Step 6: Final answer
   x = 1,201.73