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Finding the Fourth Proportional to 989.74, 1,365.91 and 641.44

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Solution

The fourth proportional to 989.74, 1,365.91 and 641.44 is: 885.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.74 : 1,365.91 = 641.44 : x
  2. Step 2: Convert to fraction form
    989.74/1,365.91 = 641.44/x
  3. Step 3: Cross multiply
    989.74x = 1,365.91 × 641.44
  4. Step 4: Simplify right side
    989.74x = 876,149.31
  5. Step 5: Solve for x
    x = 876,149.31/989.74
  6. Step 6: Final answer
    x = 885.23

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1.5x scale

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.