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Finding the Fourth Proportional to 1,281.05, 1,921.80 and 631.79

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Solution

The fourth proportional to 1,281.05, 1,921.80 and 631.79 is: 947.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.05 : 1,921.80 = 631.79 : x
  2. Step 2: Convert to fraction form
    1,281.05/1,921.80 = 631.79/x
  3. Step 3: Cross multiply
    1,281.05x = 1,921.80 × 631.79
  4. Step 4: Simplify right side
    1,281.05x = 1,214,164.41
  5. Step 5: Solve for x
    x = 1,214,164.41/1,281.05
  6. Step 6: Final answer
    x = 947.79

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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.