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Finding the Fourth Proportional to 1,211.81, 1,817.64 and 431.78

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Solution

The fourth proportional to 1,211.81, 1,817.64 and 431.78 is: 647.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.81 : 1,817.64 = 431.78 : x
  2. Step 2: Convert to fraction form
    1,211.81/1,817.64 = 431.78/x
  3. Step 3: Cross multiply
    1,211.81x = 1,817.64 × 431.78
  4. Step 4: Simplify right side
    1,211.81x = 784,811.51
  5. Step 5: Solve for x
    x = 784,811.51/1,211.81
  6. Step 6: Final answer
    x = 647.64

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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.