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Finding the Fourth Proportional to 1,287.72, 1,932 and 518.28

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Solution

The fourth proportional to 1,287.72, 1,932 and 518.28 is: 777.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.72 : 1,932 = 518.28 : x
  2. Step 2: Convert to fraction form
    1,287.72/1,932 = 518.28/x
  3. Step 3: Cross multiply
    1,287.72x = 1,932 × 518.28
  4. Step 4: Simplify right side
    1,287.72x = 1,001,316.96
  5. Step 5: Solve for x
    x = 1,001,316.96/1,287.72
  6. Step 6: Final answer
    x = 777.59

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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.