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Finding the Fourth Proportional to 1,121.87, 1,681.32 and 860.87

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Solution

The fourth proportional to 1,121.87, 1,681.32 and 860.87 is: 1,290.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.87 : 1,681.32 = 860.87 : x
  2. Step 2: Convert to fraction form
    1,121.87/1,681.32 = 860.87/x
  3. Step 3: Cross multiply
    1,121.87x = 1,681.32 × 860.87
  4. Step 4: Simplify right side
    1,121.87x = 1,447,385.24
  5. Step 5: Solve for x
    x = 1,447,385.24/1,121.87
  6. Step 6: Final answer
    x = 1,290.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.