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Finding the Fourth Proportional to 990.96, 1,486.89 and 406.40

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Solution

The fourth proportional to 990.96, 1,486.89 and 406.40 is: 609.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.96 : 1,486.89 = 406.40 : x
  2. Step 2: Convert to fraction form
    990.96/1,486.89 = 406.40/x
  3. Step 3: Cross multiply
    990.96x = 1,486.89 × 406.40
  4. Step 4: Simplify right side
    990.96x = 604,264.66
  5. Step 5: Solve for x
    x = 604,264.66/990.96
  6. Step 6: Final answer
    x = 609.78

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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.