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Finding the Fourth Proportional to 870.30, 1,306.65 and 687.90

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Solution

The fourth proportional to 870.30, 1,306.65 and 687.90 is: 1,032.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.30 : 1,306.65 = 687.90 : x
  2. Step 2: Convert to fraction form
    870.30/1,306.65 = 687.90/x
  3. Step 3: Cross multiply
    870.30x = 1,306.65 × 687.90
  4. Step 4: Simplify right side
    870.30x = 898,844.54
  5. Step 5: Solve for x
    x = 898,844.54/870.30
  6. Step 6: Final answer
    x = 1,032.80

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.