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Finding the Fourth Proportional to 1,189.28, 1,641.20 and 665.31

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Solution

The fourth proportional to 1,189.28, 1,641.20 and 665.31 is: 918.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,189.28 : 1,641.20 = 665.31 : x
  2. Step 2: Convert to fraction form
    1,189.28/1,641.20 = 665.31/x
  3. Step 3: Cross multiply
    1,189.28x = 1,641.20 × 665.31
  4. Step 4: Simplify right side
    1,189.28x = 1,091,909.60
  5. Step 5: Solve for x
    x = 1,091,909.60/1,189.28
  6. Step 6: Final answer
    x = 918.12

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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.