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Finding the Fourth Proportional to 1,215.72, 1,677.78 and 691.78

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Solution

The fourth proportional to 1,215.72, 1,677.78 and 691.78 is: 954.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,215.72 : 1,677.78 = 691.78 : x
  2. Step 2: Convert to fraction form
    1,215.72/1,677.78 = 691.78/x
  3. Step 3: Cross multiply
    1,215.72x = 1,677.78 × 691.78
  4. Step 4: Simplify right side
    1,215.72x = 1,160,654.65
  5. Step 5: Solve for x
    x = 1,160,654.65/1,215.72
  6. Step 6: Final answer
    x = 954.71

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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.