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Finding the Fourth Proportional to 1,189.75, 1,641.86 and 665.91

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Solution

The fourth proportional to 1,189.75, 1,641.86 and 665.91 is: 918.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,189.75 : 1,641.86 = 665.91 : x
  2. Step 2: Convert to fraction form
    1,189.75/1,641.86 = 665.91/x
  3. Step 3: Cross multiply
    1,189.75x = 1,641.86 × 665.91
  4. Step 4: Simplify right side
    1,189.75x = 1,093,330.99
  5. Step 5: Solve for x
    x = 1,093,330.99/1,189.75
  6. Step 6: Final answer
    x = 918.96

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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.