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Finding the Fourth Proportional to 1,272.40, 1,908.78 and 647.92

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Solution

The fourth proportional to 1,272.40, 1,908.78 and 647.92 is: 971.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,272.40 : 1,908.78 = 647.92 : x
  2. Step 2: Convert to fraction form
    1,272.40/1,908.78 = 647.92/x
  3. Step 3: Cross multiply
    1,272.40x = 1,908.78 × 647.92
  4. Step 4: Simplify right side
    1,272.40x = 1,236,736.74
  5. Step 5: Solve for x
    x = 1,236,736.74/1,272.40
  6. Step 6: Final answer
    x = 971.97

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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.