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Finding the Fourth Proportional to 990.21, 1,485.15 and 405.19

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Solution

The fourth proportional to 990.21, 1,485.15 and 405.19 is: 607.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.21 : 1,485.15 = 405.19 : x
  2. Step 2: Convert to fraction form
    990.21/1,485.15 = 405.19/x
  3. Step 3: Cross multiply
    990.21x = 1,485.15 × 405.19
  4. Step 4: Simplify right side
    990.21x = 601,767.93
  5. Step 5: Solve for x
    x = 601,767.93/990.21
  6. Step 6: Final answer
    x = 607.72

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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.