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Finding the Fourth Proportional to 874.40, 1,311.28 and 387.28

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Solution

The fourth proportional to 874.40, 1,311.28 and 387.28 is: 580.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    874.40 : 1,311.28 = 387.28 : x
  2. Step 2: Convert to fraction form
    874.40/1,311.28 = 387.28/x
  3. Step 3: Cross multiply
    874.40x = 1,311.28 × 387.28
  4. Step 4: Simplify right side
    874.40x = 507,832.52
  5. Step 5: Solve for x
    x = 507,832.52/874.40
  6. Step 6: Final answer
    x = 580.78

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Double scale
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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.