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Finding the Fourth Proportional to 1,380.65, 1,905.28 and 821.54

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Solution

The fourth proportional to 1,380.65, 1,905.28 and 821.54 is: 1,133.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.65 : 1,905.28 = 821.54 : x
  2. Step 2: Convert to fraction form
    1,380.65/1,905.28 = 821.54/x
  3. Step 3: Cross multiply
    1,380.65x = 1,905.28 × 821.54
  4. Step 4: Simplify right side
    1,380.65x = 1,565,266.44
  5. Step 5: Solve for x
    x = 1,565,266.44/1,380.65
  6. Step 6: Final answer
    x = 1,133.72

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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.