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Finding the Fourth Proportional to 643.61, 965.70 and 253.90

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Solution

The fourth proportional to 643.61, 965.70 and 253.90 is: 380.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.61 : 965.70 = 253.90 : x
  2. Step 2: Convert to fraction form
    643.61/965.70 = 253.90/x
  3. Step 3: Cross multiply
    643.61x = 965.70 × 253.90
  4. Step 4: Simplify right side
    643.61x = 245,188.82
  5. Step 5: Solve for x
    x = 245,188.82/643.61
  6. Step 6: Final answer
    x = 380.96

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Half scale
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Double scale
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Similar ratio
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1.5x scale

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.