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Finding the Fourth Proportional to 1,280.91, 1,767.57 and 721.28

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Solution

The fourth proportional to 1,280.91, 1,767.57 and 721.28 is: 995.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.91 : 1,767.57 = 721.28 : x
  2. Step 2: Convert to fraction form
    1,280.91/1,767.57 = 721.28/x
  3. Step 3: Cross multiply
    1,280.91x = 1,767.57 × 721.28
  4. Step 4: Simplify right side
    1,280.91x = 1,274,913.69
  5. Step 5: Solve for x
    x = 1,274,913.69/1,280.91
  6. Step 6: Final answer
    x = 995.32

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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 (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.