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Finding the Fourth Proportional to 1,390.07, 1,918.28 and 769.07

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Solution

The fourth proportional to 1,390.07, 1,918.28 and 769.07 is: 1,061.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.07 : 1,918.28 = 769.07 : x
  2. Step 2: Convert to fraction form
    1,390.07/1,918.28 = 769.07/x
  3. Step 3: Cross multiply
    1,390.07x = 1,918.28 × 769.07
  4. Step 4: Simplify right side
    1,390.07x = 1,475,291.60
  5. Step 5: Solve for x
    x = 1,475,291.60/1,390.07
  6. Step 6: Final answer
    x = 1,061.31

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.