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Finding the Fourth Proportional to 857.10, 1,284.30 and 638.40

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Solution

The fourth proportional to 857.10, 1,284.30 and 638.40 is: 956.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    857.10 : 1,284.30 = 638.40 : x
  2. Step 2: Convert to fraction form
    857.10/1,284.30 = 638.40/x
  3. Step 3: Cross multiply
    857.10x = 1,284.30 × 638.40
  4. Step 4: Simplify right side
    857.10x = 819,897.12
  5. Step 5: Solve for x
    x = 819,897.12/857.10
  6. Step 6: Final answer
    x = 956.59

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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.