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Finding the Fourth Proportional to 1,209.47, 1,667.70 and 987.74

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Solution

The fourth proportional to 1,209.47, 1,667.70 and 987.74 is: 1,361.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,209.47 : 1,667.70 = 987.74 : x
  2. Step 2: Convert to fraction form
    1,209.47/1,667.70 = 987.74/x
  3. Step 3: Cross multiply
    1,209.47x = 1,667.70 × 987.74
  4. Step 4: Simplify right side
    1,209.47x = 1,647,245.66
  5. Step 5: Solve for x
    x = 1,647,245.66/1,209.47
  6. Step 6: Final answer
    x = 1,361.95

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.