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Finding the Fourth Proportional to 1,287.45, 1,928.55 and 869.70

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Solution

The fourth proportional to 1,287.45, 1,928.55 and 869.70 is: 1,302.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.45 : 1,928.55 = 869.70 : x
  2. Step 2: Convert to fraction form
    1,287.45/1,928.55 = 869.70/x
  3. Step 3: Cross multiply
    1,287.45x = 1,928.55 × 869.70
  4. Step 4: Simplify right side
    1,287.45x = 1,677,259.94
  5. Step 5: Solve for x
    x = 1,677,259.94/1,287.45
  6. Step 6: Final answer
    x = 1,302.78

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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.