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Finding the Fourth Proportional to 1,387.46, 2,081.42 and 647.81

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Solution

The fourth proportional to 1,387.46, 2,081.42 and 647.81 is: 971.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,387.46 : 2,081.42 = 647.81 : x
  2. Step 2: Convert to fraction form
    1,387.46/2,081.42 = 647.81/x
  3. Step 3: Cross multiply
    1,387.46x = 2,081.42 × 647.81
  4. Step 4: Simplify right side
    1,387.46x = 1,348,361.45
  5. Step 5: Solve for x
    x = 1,348,361.45/1,387.46
  6. Step 6: Final answer
    x = 971.82

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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.