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Finding the Fourth Proportional to 1,187.81, 1,639.57 and 690.61

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Solution

The fourth proportional to 1,187.81, 1,639.57 and 690.61 is: 953.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.81 : 1,639.57 = 690.61 : x
  2. Step 2: Convert to fraction form
    1,187.81/1,639.57 = 690.61/x
  3. Step 3: Cross multiply
    1,187.81x = 1,639.57 × 690.61
  4. Step 4: Simplify right side
    1,187.81x = 1,132,306.96
  5. Step 5: Solve for x
    x = 1,132,306.96/1,187.81
  6. Step 6: Final answer
    x = 953.27

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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.