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Finding the Fourth Proportional to 989.76, 1,366.38 and 640.68

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Solution

The fourth proportional to 989.76, 1,366.38 and 640.68 is: 884.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.76 : 1,366.38 = 640.68 : x
  2. Step 2: Convert to fraction form
    989.76/1,366.38 = 640.68/x
  3. Step 3: Cross multiply
    989.76x = 1,366.38 × 640.68
  4. Step 4: Simplify right side
    989.76x = 875,412.34
  5. Step 5: Solve for x
    x = 875,412.34/989.76
  6. Step 6: Final answer
    x = 884.47

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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.