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Finding the Fourth Proportional to 1,319.78, 1,979.67 and 345.86

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Solution

The fourth proportional to 1,319.78, 1,979.67 and 345.86 is: 518.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.78 : 1,979.67 = 345.86 : x
  2. Step 2: Convert to fraction form
    1,319.78/1,979.67 = 345.86/x
  3. Step 3: Cross multiply
    1,319.78x = 1,979.67 × 345.86
  4. Step 4: Simplify right side
    1,319.78x = 684,688.67
  5. Step 5: Solve for x
    x = 684,688.67/1,319.78
  6. Step 6: Final answer
    x = 518.79

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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.