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Finding the Fourth Proportional to 1,034.72, 1,428.12 and 642

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Solution

The fourth proportional to 1,034.72, 1,428.12 and 642 is: 886.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,034.72 : 1,428.12 = 642 : x
  2. Step 2: Convert to fraction form
    1,034.72/1,428.12 = 642/x
  3. Step 3: Cross multiply
    1,034.72x = 1,428.12 × 642
  4. Step 4: Simplify right side
    1,034.72x = 916,853.04
  5. Step 5: Solve for x
    x = 916,853.04/1,034.72
  6. Step 6: Final answer
    x = 886.09

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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.