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Finding the Fourth Proportional to 1,222.70, 1,687.31 and 691.57

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Solution

The fourth proportional to 1,222.70, 1,687.31 and 691.57 is: 954.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,222.70 : 1,687.31 = 691.57 : x
  2. Step 2: Convert to fraction form
    1,222.70/1,687.31 = 691.57/x
  3. Step 3: Cross multiply
    1,222.70x = 1,687.31 × 691.57
  4. Step 4: Simplify right side
    1,222.70x = 1,166,888.72
  5. Step 5: Solve for x
    x = 1,166,888.72/1,222.70
  6. Step 6: Final answer
    x = 954.36

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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.