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Finding the Fourth Proportional to 1,320.70, 1,981.08 and 455

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Solution

The fourth proportional to 1,320.70, 1,981.08 and 455 is: 682.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.70 : 1,981.08 = 455 : x
  2. Step 2: Convert to fraction form
    1,320.70/1,981.08 = 455/x
  3. Step 3: Cross multiply
    1,320.70x = 1,981.08 × 455
  4. Step 4: Simplify right side
    1,320.70x = 901,391.40
  5. Step 5: Solve for x
    x = 901,391.40/1,320.70
  6. Step 6: Final answer
    x = 682.51

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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.