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Finding the Fourth Proportional to 1,319.68, 1,979.20 and 407.68

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Solution

The fourth proportional to 1,319.68, 1,979.20 and 407.68 is: 611.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.68 : 1,979.20 = 407.68 : x
  2. Step 2: Convert to fraction form
    1,319.68/1,979.20 = 407.68/x
  3. Step 3: Cross multiply
    1,319.68x = 1,979.20 × 407.68
  4. Step 4: Simplify right side
    1,319.68x = 806,880.26
  5. Step 5: Solve for x
    x = 806,880.26/1,319.68
  6. Step 6: Final answer
    x = 611.42

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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.