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Finding the Fourth Proportional to 643.89, 965.75 and 385.70

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Solution

The fourth proportional to 643.89, 965.75 and 385.70 is: 578.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.89 : 965.75 = 385.70 : x
  2. Step 2: Convert to fraction form
    643.89/965.75 = 385.70/x
  3. Step 3: Cross multiply
    643.89x = 965.75 × 385.70
  4. Step 4: Simplify right side
    643.89x = 372,489.78
  5. Step 5: Solve for x
    x = 372,489.78/643.89
  6. Step 6: Final answer
    x = 578.50

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Half scale
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Double scale
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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.