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Finding the Fourth Proportional to 990.88, 1,486.41 and 405.75

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Solution

The fourth proportional to 990.88, 1,486.41 and 405.75 is: 608.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.88 : 1,486.41 = 405.75 : x
  2. Step 2: Convert to fraction form
    990.88/1,486.41 = 405.75/x
  3. Step 3: Cross multiply
    990.88x = 1,486.41 × 405.75
  4. Step 4: Simplify right side
    990.88x = 603,110.86
  5. Step 5: Solve for x
    x = 603,110.86/990.88
  6. Step 6: Final answer
    x = 608.66

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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.