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Finding the Fourth Proportional to 1,012.90, 1,397.73 and 639.70

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Solution

The fourth proportional to 1,012.90, 1,397.73 and 639.70 is: 882.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,012.90 : 1,397.73 = 639.70 : x
  2. Step 2: Convert to fraction form
    1,012.90/1,397.73 = 639.70/x
  3. Step 3: Cross multiply
    1,012.90x = 1,397.73 × 639.70
  4. Step 4: Simplify right side
    1,012.90x = 894,127.88
  5. Step 5: Solve for x
    x = 894,127.88/1,012.90
  6. Step 6: Final answer
    x = 882.74

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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.