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Finding the Fourth Proportional to 989.91, 1,486.68 and 665.51

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Solution

The fourth proportional to 989.91, 1,486.68 and 665.51 is: 999.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.91 : 1,486.68 = 665.51 : x
  2. Step 2: Convert to fraction form
    989.91/1,486.68 = 665.51/x
  3. Step 3: Cross multiply
    989.91x = 1,486.68 × 665.51
  4. Step 4: Simplify right side
    989.91x = 989,392.97
  5. Step 5: Solve for x
    x = 989,392.97/989.91
  6. Step 6: Final answer
    x = 999.48

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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.