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Finding the Fourth Proportional to 989.79, 1,486.99 and 579.21

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Solution

The fourth proportional to 989.79, 1,486.99 and 579.21 is: 870.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.79 : 1,486.99 = 579.21 : x
  2. Step 2: Convert to fraction form
    989.79/1,486.99 = 579.21/x
  3. Step 3: Cross multiply
    989.79x = 1,486.99 × 579.21
  4. Step 4: Simplify right side
    989.79x = 861,279.48
  5. Step 5: Solve for x
    x = 861,279.48/989.79
  6. Step 6: Final answer
    x = 870.16

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.