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Finding the Fourth Proportional to 861.96, 1,189.78 and 665.13

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Solution

The fourth proportional to 861.96, 1,189.78 and 665.13 is: 918.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.96 : 1,189.78 = 665.13 : x
  2. Step 2: Convert to fraction form
    861.96/1,189.78 = 665.13/x
  3. Step 3: Cross multiply
    861.96x = 1,189.78 × 665.13
  4. Step 4: Simplify right side
    861.96x = 791,356.71
  5. Step 5: Solve for x
    x = 791,356.71/861.96
  6. Step 6: Final answer
    x = 918.09

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Double scale
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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.