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Finding the Fourth Proportional to 1,005.75, 1,509.30 and 428.76

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Solution

The fourth proportional to 1,005.75, 1,509.30 and 428.76 is: 643.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,005.75 : 1,509.30 = 428.76 : x
  2. Step 2: Convert to fraction form
    1,005.75/1,509.30 = 428.76/x
  3. Step 3: Cross multiply
    1,005.75x = 1,509.30 × 428.76
  4. Step 4: Simplify right side
    1,005.75x = 647,127.47
  5. Step 5: Solve for x
    x = 647,127.47/1,005.75
  6. Step 6: Final answer
    x = 643.43

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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.