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Finding the Fourth Proportional to 1,139, 1,708.50 and 408.40

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Solution

The fourth proportional to 1,139, 1,708.50 and 408.40 is: 612.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139 : 1,708.50 = 408.40 : x
  2. Step 2: Convert to fraction form
    1,139/1,708.50 = 408.40/x
  3. Step 3: Cross multiply
    1,139x = 1,708.50 × 408.40
  4. Step 4: Simplify right side
    1,139x = 697,751.40
  5. Step 5: Solve for x
    x = 697,751.40/1,139
  6. Step 6: Final answer
    x = 612.60

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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.