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Finding the Fourth Proportional to 990.27, 1,485.42 and 259.85

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Solution

The fourth proportional to 990.27, 1,485.42 and 259.85 is: 389.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.27 : 1,485.42 = 259.85 : x
  2. Step 2: Convert to fraction form
    990.27/1,485.42 = 259.85/x
  3. Step 3: Cross multiply
    990.27x = 1,485.42 × 259.85
  4. Step 4: Simplify right side
    990.27x = 385,985.12
  5. Step 5: Solve for x
    x = 385,985.12/990.27
  6. Step 6: Final answer
    x = 389.78

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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.