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Finding the Fourth Proportional to 1,285.40, 1,926.28 and 515

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Solution

The fourth proportional to 1,285.40, 1,926.28 and 515 is: 771.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,285.40 : 1,926.28 = 515 : x
  2. Step 2: Convert to fraction form
    1,285.40/1,926.28 = 515/x
  3. Step 3: Cross multiply
    1,285.40x = 1,926.28 × 515
  4. Step 4: Simplify right side
    1,285.40x = 992,034.20
  5. Step 5: Solve for x
    x = 992,034.20/1,285.40
  6. Step 6: Final answer
    x = 771.77

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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.