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Finding the Fourth Proportional to 993.90, 1,371.80 and 643.98

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Solution

The fourth proportional to 993.90, 1,371.80 and 643.98 is: 888.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    993.90 : 1,371.80 = 643.98 : x
  2. Step 2: Convert to fraction form
    993.90/1,371.80 = 643.98/x
  3. Step 3: Cross multiply
    993.90x = 1,371.80 × 643.98
  4. Step 4: Simplify right side
    993.90x = 883,411.76
  5. Step 5: Solve for x
    x = 883,411.76/993.90
  6. Step 6: Final answer
    x = 888.83

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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.