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Finding the Fourth Proportional to 1,440, 1,987.20 and 819.12

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Solution

The fourth proportional to 1,440, 1,987.20 and 819.12 is: 1,130.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,440 : 1,987.20 = 819.12 : x
  2. Step 2: Convert to fraction form
    1,440/1,987.20 = 819.12/x
  3. Step 3: Cross multiply
    1,440x = 1,987.20 × 819.12
  4. Step 4: Simplify right side
    1,440x = 1,627,755.26
  5. Step 5: Solve for x
    x = 1,627,755.26/1,440
  6. Step 6: Final answer
    x = 1,130.39

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.