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Finding the Fourth Proportional to 990.60, 1,485.99 and 405.57

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Solution

The fourth proportional to 990.60, 1,485.99 and 405.57 is: 608.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.60 : 1,485.99 = 405.57 : x
  2. Step 2: Convert to fraction form
    990.60/1,485.99 = 405.57/x
  3. Step 3: Cross multiply
    990.60x = 1,485.99 × 405.57
  4. Step 4: Simplify right side
    990.60x = 602,672.96
  5. Step 5: Solve for x
    x = 602,672.96/990.60
  6. Step 6: Final answer
    x = 608.39

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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.