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Finding the Fourth Proportional to 990.30, 1,485.50 and 259.87

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Solution

The fourth proportional to 990.30, 1,485.50 and 259.87 is: 389.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    990.30 : 1,485.50 = 259.87 : x
  2. Step 2: Convert to fraction form
    990.30/1,485.50 = 259.87/x
  3. Step 3: Cross multiply
    990.30x = 1,485.50 × 259.87
  4. Step 4: Simplify right side
    990.30x = 386,036.89
  5. Step 5: Solve for x
    x = 386,036.89/990.30
  6. Step 6: Final answer
    x = 389.82

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Double scale
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Similar ratio
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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.