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Finding the Fourth Proportional to 1,138.72, 1,707.63 and 489

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Solution

The fourth proportional to 1,138.72, 1,707.63 and 489 is: 733.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,138.72 : 1,707.63 = 489 : x
  2. Step 2: Convert to fraction form
    1,138.72/1,707.63 = 489/x
  3. Step 3: Cross multiply
    1,138.72x = 1,707.63 × 489
  4. Step 4: Simplify right side
    1,138.72x = 835,031.07
  5. Step 5: Solve for x
    x = 835,031.07/1,138.72
  6. Step 6: Final answer
    x = 733.31

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.