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Finding the Fourth Proportional to 1,280.78, 1,768.02 and 861.38

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Solution

The fourth proportional to 1,280.78, 1,768.02 and 861.38 is: 1,189.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.78 : 1,768.02 = 861.38 : x
  2. Step 2: Convert to fraction form
    1,280.78/1,768.02 = 861.38/x
  3. Step 3: Cross multiply
    1,280.78x = 1,768.02 × 861.38
  4. Step 4: Simplify right side
    1,280.78x = 1,522,931.46
  5. Step 5: Solve for x
    x = 1,522,931.46/1,280.78
  6. Step 6: Final answer
    x = 1,189.06

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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.