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Finding the Fourth Proportional to 1,005, 1,388 and 691.10

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Solution

The fourth proportional to 1,005, 1,388 and 691.10 is: 954.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,005 : 1,388 = 691.10 : x
  2. Step 2: Convert to fraction form
    1,005/1,388 = 691.10/x
  3. Step 3: Cross multiply
    1,005x = 1,388 × 691.10
  4. Step 4: Simplify right side
    1,005x = 959,246.80
  5. Step 5: Solve for x
    x = 959,246.80/1,005
  6. Step 6: Final answer
    x = 954.47

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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.