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Finding the Fourth Proportional to 871.81, 1,307.72 and 821.10

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Solution

The fourth proportional to 871.81, 1,307.72 and 821.10 is: 1,231.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.81 : 1,307.72 = 821.10 : x
  2. Step 2: Convert to fraction form
    871.81/1,307.72 = 821.10/x
  3. Step 3: Cross multiply
    871.81x = 1,307.72 × 821.10
  4. Step 4: Simplify right side
    871.81x = 1,073,768.89
  5. Step 5: Solve for x
    x = 1,073,768.89/871.81
  6. Step 6: Final answer
    x = 1,231.65

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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.