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Finding the Fourth Proportional to 1,189.18, 1,640.88 and 665.20

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Solution

The fourth proportional to 1,189.18, 1,640.88 and 665.20 is: 917.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,189.18 : 1,640.88 = 665.20 : x
  2. Step 2: Convert to fraction form
    1,189.18/1,640.88 = 665.20/x
  3. Step 3: Cross multiply
    1,189.18x = 1,640.88 × 665.20
  4. Step 4: Simplify right side
    1,189.18x = 1,091,513.38
  5. Step 5: Solve for x
    x = 1,091,513.38/1,189.18
  6. Step 6: Final answer
    x = 917.87

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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.