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Finding the Fourth Proportional to 387.40, 580.64 and 143.78

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Solution

The fourth proportional to 387.40, 580.64 and 143.78 is: 215.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.40 : 580.64 = 143.78 : x
  2. Step 2: Convert to fraction form
    387.40/580.64 = 143.78/x
  3. Step 3: Cross multiply
    387.40x = 580.64 × 143.78
  4. Step 4: Simplify right side
    387.40x = 83,484.42
  5. Step 5: Solve for x
    x = 83,484.42/387.40
  6. Step 6: Final answer
    x = 215.50

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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.