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Finding the Fourth Proportional to 1,319.09, 1,978.69 and 345.20

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Solution

The fourth proportional to 1,319.09, 1,978.69 and 345.20 is: 517.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.09 : 1,978.69 = 345.20 : x
  2. Step 2: Convert to fraction form
    1,319.09/1,978.69 = 345.20/x
  3. Step 3: Cross multiply
    1,319.09x = 1,978.69 × 345.20
  4. Step 4: Simplify right side
    1,319.09x = 683,043.79
  5. Step 5: Solve for x
    x = 683,043.79/1,319.09
  6. Step 6: Final answer
    x = 517.81

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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.