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Finding the Fourth Proportional to 1,280.76, 1,767.44 and 728.76

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Solution

The fourth proportional to 1,280.76, 1,767.44 and 728.76 is: 1,005.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.76 : 1,767.44 = 728.76 : x
  2. Step 2: Convert to fraction form
    1,280.76/1,767.44 = 728.76/x
  3. Step 3: Cross multiply
    1,280.76x = 1,767.44 × 728.76
  4. Step 4: Simplify right side
    1,280.76x = 1,288,039.57
  5. Step 5: Solve for x
    x = 1,288,039.57/1,280.76
  6. Step 6: Final answer
    x = 1,005.68

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Half 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.