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Finding the Fourth Proportional to 1,187.47, 1,638.66 and 690.31

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Solution

The fourth proportional to 1,187.47, 1,638.66 and 690.31 is: 952.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.47 : 1,638.66 = 690.31 : x
  2. Step 2: Convert to fraction form
    1,187.47/1,638.66 = 690.31/x
  3. Step 3: Cross multiply
    1,187.47x = 1,638.66 × 690.31
  4. Step 4: Simplify right side
    1,187.47x = 1,131,183.38
  5. Step 5: Solve for x
    x = 1,131,183.38/1,187.47
  6. Step 6: Final answer
    x = 952.60

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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.