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Finding the Fourth Proportional to 861.74, 1,189.42 and 551.78

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Solution

The fourth proportional to 861.74, 1,189.42 and 551.78 is: 761.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.74 : 1,189.42 = 551.78 : x
  2. Step 2: Convert to fraction form
    861.74/1,189.42 = 551.78/x
  3. Step 3: Cross multiply
    861.74x = 1,189.42 × 551.78
  4. Step 4: Simplify right side
    861.74x = 656,298.17
  5. Step 5: Solve for x
    x = 656,298.17/861.74
  6. Step 6: Final answer
    x = 761.60

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1.5x scale

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.