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Finding the Fourth Proportional to 1,218.17, 1,679.81 and 920.12

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Solution

The fourth proportional to 1,218.17, 1,679.81 and 920.12 is: 1,268.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.17 : 1,679.81 = 920.12 : x
  2. Step 2: Convert to fraction form
    1,218.17/1,679.81 = 920.12/x
  3. Step 3: Cross multiply
    1,218.17x = 1,679.81 × 920.12
  4. Step 4: Simplify right side
    1,218.17x = 1,545,613.78
  5. Step 5: Solve for x
    x = 1,545,613.78/1,218.17
  6. Step 6: Final answer
    x = 1,268.80

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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.