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Finding the Fourth Proportional to 1,389, 2,078.58 and 869.25

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Solution

The fourth proportional to 1,389, 2,078.58 and 869.25 is: 1,300.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389 : 2,078.58 = 869.25 : x
  2. Step 2: Convert to fraction form
    1,389/2,078.58 = 869.25/x
  3. Step 3: Cross multiply
    1,389x = 2,078.58 × 869.25
  4. Step 4: Simplify right side
    1,389x = 1,806,805.67
  5. Step 5: Solve for x
    x = 1,806,805.67/1,389
  6. Step 6: Final answer
    x = 1,300.80

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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.