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Finding the Fourth Proportional to 1,391.80, 1,920 and 920.52

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Solution

The fourth proportional to 1,391.80, 1,920 and 920.52 is: 1,269.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.80 : 1,920 = 920.52 : x
  2. Step 2: Convert to fraction form
    1,391.80/1,920 = 920.52/x
  3. Step 3: Cross multiply
    1,391.80x = 1,920 × 920.52
  4. Step 4: Simplify right side
    1,391.80x = 1,767,398.40
  5. Step 5: Solve for x
    x = 1,767,398.40/1,391.80
  6. Step 6: Final answer
    x = 1,269.87

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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.