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Finding the Fourth Proportional to 1,021.80, 1,532.70 and 405.20

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Solution

The fourth proportional to 1,021.80, 1,532.70 and 405.20 is: 607.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,021.80 : 1,532.70 = 405.20 : x
  2. Step 2: Convert to fraction form
    1,021.80/1,532.70 = 405.20/x
  3. Step 3: Cross multiply
    1,021.80x = 1,532.70 × 405.20
  4. Step 4: Simplify right side
    1,021.80x = 621,042.38
  5. Step 5: Solve for x
    x = 621,042.38/1,021.80
  6. Step 6: Final answer
    x = 607.79

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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.