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Finding the Fourth Proportional to 1,386.78, 2,080.49 and 412.87

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Solution

The fourth proportional to 1,386.78, 2,080.49 and 412.87 is: 619.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.78 : 2,080.49 = 412.87 : x
  2. Step 2: Convert to fraction form
    1,386.78/2,080.49 = 412.87/x
  3. Step 3: Cross multiply
    1,386.78x = 2,080.49 × 412.87
  4. Step 4: Simplify right side
    1,386.78x = 858,971.91
  5. Step 5: Solve for x
    x = 858,971.91/1,386.78
  6. Step 6: Final answer
    x = 619.40

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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.