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Finding the Fourth Proportional to 643.40, 965.10 and 521.90

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Solution

The fourth proportional to 643.40, 965.10 and 521.90 is: 782.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.40 : 965.10 = 521.90 : x
  2. Step 2: Convert to fraction form
    643.40/965.10 = 521.90/x
  3. Step 3: Cross multiply
    643.40x = 965.10 × 521.90
  4. Step 4: Simplify right side
    643.40x = 503,685.69
  5. Step 5: Solve for x
    x = 503,685.69/643.40
  6. Step 6: Final answer
    x = 782.85

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Double scale
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Similar ratio
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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.