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Finding the Fourth Proportional to 1,187.27, 1,781.42 and 638.81

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Solution

The fourth proportional to 1,187.27, 1,781.42 and 638.81 is: 958.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.27 : 1,781.42 = 638.81 : x
  2. Step 2: Convert to fraction form
    1,187.27/1,781.42 = 638.81/x
  3. Step 3: Cross multiply
    1,187.27x = 1,781.42 × 638.81
  4. Step 4: Simplify right side
    1,187.27x = 1,137,988.91
  5. Step 5: Solve for x
    x = 1,137,988.91/1,187.27
  6. Step 6: Final answer
    x = 958.49

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.