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Finding the Fourth Proportional to 1,387.60, 2,084.40 and 840.04

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Solution

The fourth proportional to 1,387.60, 2,084.40 and 840.04 is: 1,261.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.60 : 2,084.40 = 840.04 : x
  2. Step 2: Convert to fraction form
    1,387.60/2,084.40 = 840.04/x
  3. Step 3: Cross multiply
    1,387.60x = 2,084.40 × 840.04
  4. Step 4: Simplify right side
    1,387.60x = 1,750,979.38
  5. Step 5: Solve for x
    x = 1,750,979.38/1,387.60
  6. Step 6: Final answer
    x = 1,261.88

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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.