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Finding the Fourth Proportional to 1,280.76, 1,767.44 and 815

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Solution

The fourth proportional to 1,280.76, 1,767.44 and 815 is: 1,124.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.76 : 1,767.44 = 815 : x
  2. Step 2: Convert to fraction form
    1,280.76/1,767.44 = 815/x
  3. Step 3: Cross multiply
    1,280.76x = 1,767.44 × 815
  4. Step 4: Simplify right side
    1,280.76x = 1,440,463.60
  5. Step 5: Solve for x
    x = 1,440,463.60/1,280.76
  6. Step 6: Final answer
    x = 1,124.69

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Double scale
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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.