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Finding the Fourth Proportional to 1,290.65, 1,781.16 and 731.09

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Solution

The fourth proportional to 1,290.65, 1,781.16 and 731.09 is: 1,008.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.65 : 1,781.16 = 731.09 : x
  2. Step 2: Convert to fraction form
    1,290.65/1,781.16 = 731.09/x
  3. Step 3: Cross multiply
    1,290.65x = 1,781.16 × 731.09
  4. Step 4: Simplify right side
    1,290.65x = 1,302,188.26
  5. Step 5: Solve for x
    x = 1,302,188.26/1,290.65
  6. Step 6: Final answer
    x = 1,008.94

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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.