Finding the Fourth Proportional to 1,533.21, 2,115.72 and 870.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,533.21 : 2,115.72 = 870.15 : x
2. Step 2: Convert to fraction form
   1,533.21/2,115.72 = 870.15/x
3. Step 3: Cross multiply
   1,533.21x = 2,115.72 × 870.15
4. Step 4: Simplify right side
   1,533.21x = 1,840,993.76
5. Step 5: Solve for x
   x = 1,840,993.76/1,533.21
6. Step 6: Final answer
   x = 1,200.74