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Finding the Fourth Proportional to 1,386.78, 2,079.93 and 412.65

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Solution

The fourth proportional to 1,386.78, 2,079.93 and 412.65 is: 618.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.78 : 2,079.93 = 412.65 : x
  2. Step 2: Convert to fraction form
    1,386.78/2,079.93 = 412.65/x
  3. Step 3: Cross multiply
    1,386.78x = 2,079.93 × 412.65
  4. Step 4: Simplify right side
    1,386.78x = 858,283.11
  5. Step 5: Solve for x
    x = 858,283.11/1,386.78
  6. Step 6: Final answer
    x = 618.90

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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.