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Finding the Fourth Proportional to 989.61, 1,365.80 and 616.70

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Solution

The fourth proportional to 989.61, 1,365.80 and 616.70 is: 851.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.61 : 1,365.80 = 616.70 : x
  2. Step 2: Convert to fraction form
    989.61/1,365.80 = 616.70/x
  3. Step 3: Cross multiply
    989.61x = 1,365.80 × 616.70
  4. Step 4: Simplify right side
    989.61x = 842,295.22
  5. Step 5: Solve for x
    x = 842,295.22/989.61
  6. Step 6: Final answer
    x = 851.14

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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.