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Finding the Fourth Proportional to 1,218.81, 1,681.85 and 687.66

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Solution

The fourth proportional to 1,218.81, 1,681.85 and 687.66 is: 948.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.81 : 1,681.85 = 687.66 : x
  2. Step 2: Convert to fraction form
    1,218.81/1,681.85 = 687.66/x
  3. Step 3: Cross multiply
    1,218.81x = 1,681.85 × 687.66
  4. Step 4: Simplify right side
    1,218.81x = 1,156,540.97
  5. Step 5: Solve for x
    x = 1,156,540.97/1,218.81
  6. Step 6: Final answer
    x = 948.91

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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.