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Finding the Fourth Proportional to 1,390.18, 1,918.47 and 769.18

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Solution

The fourth proportional to 1,390.18, 1,918.47 and 769.18 is: 1,061.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.18 : 1,918.47 = 769.18 : x
  2. Step 2: Convert to fraction form
    1,390.18/1,918.47 = 769.18/x
  3. Step 3: Cross multiply
    1,390.18x = 1,918.47 × 769.18
  4. Step 4: Simplify right side
    1,390.18x = 1,475,648.75
  5. Step 5: Solve for x
    x = 1,475,648.75/1,390.18
  6. Step 6: Final answer
    x = 1,061.48

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1.5x scale

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.