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Finding the Fourth Proportional to 1,311.66, 1,966.98 and 387

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Solution

The fourth proportional to 1,311.66, 1,966.98 and 387 is: 580.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.66 : 1,966.98 = 387 : x
  2. Step 2: Convert to fraction form
    1,311.66/1,966.98 = 387/x
  3. Step 3: Cross multiply
    1,311.66x = 1,966.98 × 387
  4. Step 4: Simplify right side
    1,311.66x = 761,221.26
  5. Step 5: Solve for x
    x = 761,221.26/1,311.66
  6. Step 6: Final answer
    x = 580.35

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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.