Finding the Third Proportional to 870 and 1,355.50

Step by Step Solution

1. Step 1: Write the proportion equation
   870 : 1,355.50 = 1,355.50 : x
2. Step 2: Convert to fraction form
   870/1,355.50 = 1,355.50/x
3. Step 3: Cross multiply
   870x = 1,355.50 × 1,355.50
4. Step 4: Simplify right side
   870x = 1,837,380.25
5. Step 5: Solve for x
   x = 1,837,380.25/870
6. Step 6: Final answer
   x = 2,111.93