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Finding the Fourth Proportional to 1,378.61, 1,902.35 and 781.13

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Solution

The fourth proportional to 1,378.61, 1,902.35 and 781.13 is: 1,077.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.61 : 1,902.35 = 781.13 : x
  2. Step 2: Convert to fraction form
    1,378.61/1,902.35 = 781.13/x
  3. Step 3: Cross multiply
    1,378.61x = 1,902.35 × 781.13
  4. Step 4: Simplify right side
    1,378.61x = 1,485,982.66
  5. Step 5: Solve for x
    x = 1,485,982.66/1,378.61
  6. Step 6: Final answer
    x = 1,077.88

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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.