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Finding the Fourth Proportional to 920.48, 1,380.72 and 647.79

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Solution

The fourth proportional to 920.48, 1,380.72 and 647.79 is: 971.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.48 : 1,380.72 = 647.79 : x
  2. Step 2: Convert to fraction form
    920.48/1,380.72 = 647.79/x
  3. Step 3: Cross multiply
    920.48x = 1,380.72 × 647.79
  4. Step 4: Simplify right side
    920.48x = 894,416.61
  5. Step 5: Solve for x
    x = 894,416.61/920.48
  6. Step 6: Final answer
    x = 971.69

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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.