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Finding the Fourth Proportional to 1,378.90, 2,065.38 and 647.38

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Solution

The fourth proportional to 1,378.90, 2,065.38 and 647.38 is: 969.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.90 : 2,065.38 = 647.38 : x
  2. Step 2: Convert to fraction form
    1,378.90/2,065.38 = 647.38/x
  3. Step 3: Cross multiply
    1,378.90x = 2,065.38 × 647.38
  4. Step 4: Simplify right side
    1,378.90x = 1,337,085.70
  5. Step 5: Solve for x
    x = 1,337,085.70/1,378.90
  6. Step 6: Final answer
    x = 969.68

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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.