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Finding the Fourth Proportional to 870.94, 1,299.38 and 861.76

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Solution

The fourth proportional to 870.94, 1,299.38 and 861.76 is: 1,285.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.94 : 1,299.38 = 861.76 : x
  2. Step 2: Convert to fraction form
    870.94/1,299.38 = 861.76/x
  3. Step 3: Cross multiply
    870.94x = 1,299.38 × 861.76
  4. Step 4: Simplify right side
    870.94x = 1,119,753.71
  5. Step 5: Solve for x
    x = 1,119,753.71/870.94
  6. Step 6: Final answer
    x = 1,285.68

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.