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Finding the Fourth Proportional to 1,218.85, 1,681.86 and 687.69

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Solution

The fourth proportional to 1,218.85, 1,681.86 and 687.69 is: 948.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.85 : 1,681.86 = 687.69 : x
  2. Step 2: Convert to fraction form
    1,218.85/1,681.86 = 687.69/x
  3. Step 3: Cross multiply
    1,218.85x = 1,681.86 × 687.69
  4. Step 4: Simplify right side
    1,218.85x = 1,156,600.88
  5. Step 5: Solve for x
    x = 1,156,600.88/1,218.85
  6. Step 6: Final answer
    x = 948.93

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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.